Mine just happened over the past week (sorry, very long).
DH had a cousin (RIP) whose oldest daughter came out to visit DH when she was looking into colleges in the area. He didn't remember much from that visit, except that she came across as "free-spirited". That was 8 years ago, and that side of the family doesn't really keep in touch (DH couldn't even recall which of his aunts' families this was) so I actually never heard about any of this until a few weeks ago.
Two weeks ago we got a voicemail from this girl (I'll call her CCD for cousin's crazy daughter, 26 yrs old now), saying she was flying into the area to go to a wedding in a city 3 hours away, and did we have time to meet up for dinner? Sure, okay, DH calls her back and finds out more about her plans. Turns out she's flying here, not the wedding city, because it's cheaper but her flight doesn't land on Thursday night til 8. That would put dinner at 9 at the absolute earliest, which is really late for us on a worknight. Since it also comes out that she doesn't have a hotel booked, DH offers her our guest room (after checking with me, and of course I think it's fine) and says we have plenty of food or we could order her pizza. He gives her the street address of the house but she turns down directions (even after he said it's tricky) because she'll get them somewhere. He also says, since we have to work tomorrow, we'll probably go to bed right after you get here (thinking 10-ish).
She calls from the airport at 9, having just landed (delayed flight), and says she'll just get herself a hotel room so as not to put us out since it'd be an hour at least before she could be at our house. We say no, it's fine, drive safe. DH gives her rough directions and tries to add more details, but again she says no, I'll get them somewhere. At that point I assumed she had GPS or Google maps on her phone or something. No such luck. 2 hours later, we call her because she hadn't shown. DH eventually had to talk her through every last street and turn because her grand plan had been to ask the car rental agency for one of those tri-fold maps and she'd figure it out on her own (our street is so small it doesn't show up on maps like that!). She finally shows up at midnight, fortunately not hungry because she had stopped for dinner on the way (without telling us she'd be even later, and causing us to stay up 2 hours later than we expected).
Before we went to bed, CCD offered to take us out to breakfast for our hospitality (great!), except DH can't go b/c of work. My hours are more flexible so I say okay. She says she's exhausted so will probably sleep in late-ish, like til 8 or so.
I got up around 7 Friday morning to discover CCD gone, and a note saying "I just went to the store, back in 20 min" but no time left on the note. DH left for work around 9, she still hadn't come back. She showed up about 9:30, having been gone over 3 hours (by her own admission). We went out to breakfast, and she treated the waitstaff with this kind of overly polite but condescending attitude ("Ooh, I wanted these eggs poached, not watery, could you do that for me? Oooh thank you, I knew you could do it!") and snapped at the cashier that "we are in a hurry here" when a) we weren't, having just chatted for 1.5 hours, and b) we were kept waiting because of a request CCD made!
The conversation was pretty entertaining for a while - she's a smart, ambitious person but most of her stories were about how people don't tend to live up to her expectations (exes, family members, etc). And the way she handles her personal life is really at odds with my own values, so after a while it got a little tiresome to hear about various exploits. I also discovered, since she drove us, that she's a terrible driver (subjective, of course, but it worried me to be her passenger!) and has no sense of direction.
All told, obviously not the worst visit on record - while it's rude to keep people waiting or guessing on your plans, she was really friendly, full of apologies over the late night arrival, she paid for breakfast, and heck, she's family. So we really didn't think much of it other than yeah, I guess you could call her "free-spirited."
Well, after the wedding, she drove 10 hours to go to DH's parents' lake house to spend 3-4 days there. She was invited after she called to find out how they were doing - my ILs are very hospitable and love having company. They're also pretty straitlaced and well-respected in their resort-town community (they live there year-round so are well-known to most part and full-time residents). While she was visiting there, apparently she had some confusion as to whether her return flight was out of our city or out of the city closest to the resort-town (er, who doesn't know this?). The end result was, she was flying out of our city on a late flight, so called us up to say hey, I'll be back in town on Friday, want to meet for dinner before my red-eye flight?
We say sure. She arrives at our house, after needing last minute step-by-step directions once again, but not too late. Now, DH hadn't spent much time with her previously, so this time he got the full dose and then some. Turns out, while she was at the lake house she met some cute local boys, and on her last night there she snuck out of the house to drive off with them til 5 am. She went on and on about the one she hooked up with, not quite graphically but more details than anyone needs esp at dinner! She also explicitly said that she snuck out so no one in the house would know, so as not to "sully" her hosts' reputation. She also admitted to us that she committed fraud by having one of her friends back home FedEx a package of "special cigarettes" across the US/Canada border since she ran out (weirdly, the cigs are legal here and there, just hard to find and she really really needed them for the two days before she went home).
Somewhere in there she admitted that her flight wasn't a red-eye, it was actually scheduled for the next afternoon, but she had been "planning" to just show up and fly standby (well, in her words, tell them "you and I both know there are seats on that flight, so you'll let me on, right?"). But, she was soooooo tired and obviously had no hotel plans, although she weakly said she'd find a hotel near the airport, so we said it's okay, stay in our guest room again.
So she did, and was already long gone when I got up at 6 am to let the cats out. DH and I said wow, that was altogether kind of odd, but whatever, it was probably a one-time thing and we'll likely never see her again.
Later, DH talked to his dad who said CCD actually told DH's mom and sister (who was also visiting) ALL about the hook-up guy and her other activities after all. She also pulled quite a few disappearing acts during her time there - going shopping and returning hours after she said she would, changing plans without calling, basically treating them like a hostel rather than family and contributing nothing in terms of food or effort around the house. After that, they have decided to disinvite her from any future stays. Except, as soon as CCD got home, she e-mailed them to say she and her mom would like to come visit again in August at the lake house! FIL responds, sorry but we already have company scheduled the whole time (mostly true). CCD replies, oh, no worries, now it's just me, not mom, and I'll rent a place nearby! See you in August!
We're taking bets to see if she just shows up "expecting" to rent on the spot (but really waiting to cash in on family hospitality again).