There are all sorts of things we all do but we never admit to them in public, so here's our chance to confess! (In relative anonimity because of the internet of course :p)
Alright, i'll start off with a couple of what we (most of us) do:
Saying 'i have to go' or 'i have other plans' while you don't have anything else to do but you just reeeeeeally don't feel like talking to that person or just want some quiet time.
Stalking peoples profiles (friends or crushes) just to see if they mention you. You know you do...
Saying you hate a certain song/book/movie because it's populair to hate while really.. You freaking love it. That one Kesha song you're supposed to hate but actually find quite catchy :p
Ignoring a wallpost, reply, pm, text and then saying 'oh i'm sorry! I didn't see it!' Or 'i forgot to reply!'... Mhmmm...
Picking your nose: you do that!!! Don't lie!
Saying you've done things which you haven't because you don't want to feel 'left out'
When you post something really well thought out in a populair topic but you get no replies. So you purposely quote someone else afterwards in order to get in on the debate anyway :p
Pee in the shower. Ok, maybe this goes more for guys. BUT YOU KNOW YOU'VE DONE IT AT LEAST ONCE!
Ok, plenty of more to think of. But i'll leave you all to add more :p