Most of these are applying to alcohol, but not all. I suppose I'm not very consistant with what I mean. Come to think of it, I don't even know what the order is supposed to be....
10) The bartender might ask you to leave if you aren't getting anything
9) You aren't paying for it
8) There's some left in the glass
7) To escape reality
5) Your friends are doing it
4) Your mom told you not to
3) To be social
2) To get drunk
Actually, a lot of these apply to most things...