"What are you giving up for Lent?"
"Answering nosy questions."
I've always wondered if it's rude or disrespectful to give up something for Lent when one isn't even of a faith that observes it. On the one hand, I never tell anyone anyway, so nobody knows. And, I suppose if G_d is offended, well, he'll deal with me later.
Gui - I've actually wondered the same thing. I've come to a point in my life where I've become strong enough to admit that I am not of that faith, but I still observe lent as sort of an exercise in self control, or to cleanse myself of all those sweets i eat that I don't really need. But when I say I've "given up sweets" I either get the "but you're not _______" from those who know I follow a different path or, "Oh, you must be observing Lent" from people who do not know. I don't correct anyone, but I've always wondered if my observing lent was iffy from a practitioner's POV.
Lots of people give up tempting things, for various reasons and at various times. When I was in HS, a girl I was friends with who was known for charity work would give out envelopes, suggesting that you put in $.25 daily during Lent and it would be given to a charity (she specified; I don't remember anymore). Lots of my friends participated, even Jewish ones, because they saw value in the gift and in a small sacrifice.
Someone who is very observant may privately observe that you aren't really participating in Lent as you aren't participating in its other aspect: going to church (because ultimately, Lent is meant to point us towards Easter). However, if they observe this aloud and/or rudely, well, they are rude. You are still OK.