Anyway I'm 18 and I've been buying alcohol at my local liquor stores with a real ID of a guy that looks just like me. I got paranoid the other day because as I was walking out with a case of beer the a cop car was parked next to my car. He didn't do anything but I'm just curious if they could stop me as I'm walking out the liquor store and check my id and what the penalties would be if I"m caught.

might go to jail or pay a fine or both not that bad

Nothing to bad but maybe fake identity charges and theft

fuckin 21 to drink thats gay here in canada its 18 to smoke drink gamble but i was smokin drink gamble way before i turned 18

ok well if a cop sees me walking out the liquor store with some booze and thinks I look underage can he just stop and ask to see some identification?

I'm pretty sure he can. You might get charged identity theft, false perception etc. if he does find out but I'd be more worried about going to jail on account of any charges the dude who's I.D. your carrying might have outstanding.

Regardless I wouldn't worry about it too much. I used to work at a place where we routinely acquired lost driver's licenses etc. and it was quite common for people to find the I.D.'s of others who looked like them and use 'em for alcohol purchases.