"Boss, we have a situation I would like to talk to you about. Normally I would not get into how people work but this is starting to affect me and others. I realize I may not have all the information but this is what I am observing. It appears to me that Flirty's work load has declined significantly to where the rest of us are being asked to stay late to pick up the slack. However, I also observe that she has time to sit at coworkerdude's desk and chat 5-6 times a day. He has mentioned to me that he doesn't like this particularly but doesn't know how to get her to go away so he isn't encouraging this. I would like you to observe for yourself and get her back on track with doing her assignments.
" Now, here is where I am starting to speculate...given that she came in with her stories about how she was living in a shelter with her small son and is renting a car everyday to get to work and now she doesn't feel the need to actually work so much...I am wondering if she 1) has embellished her story about how hard she has it and is using us or 2) Had to live in a shelter because she lost her previous job because she doesn't have a good work ethic. Either way I don't want pick up her slack when clearly she has time to do what she was assigned.
To the coworker, give him some phrases:
"Sorry, Flirty, I don't have time to chat. I have to get the TPS report out."
"Sorry, Flirty, I don't have time to chat. I have to call a client."
Or prearrange that when she starts walkign over you call him.
Or just call him when she sits down and he can mouth "Sorry I have to take this."
Or you can say to her "Flirty, you seem to have a lot of time to chat with Jack but yet I am staying late to do work you don't have time for. Why is that?"
or "Thank God you are here. For some reason boss gave me some of your tasks to do, but clearly you have extra time. Let me get them for you."
or 'Flirty, if you don't have anything to do it is protocol to let boss know so you can another assignment. I can mention it for you next time I see her."