Yeah I can poke the whole in the can with my thumb. Gotta be careful though...I've done it too hard before and gotten my thumb stuck in the can pretty far. heh.
the trick to that is to tilt the top of the can down, creating the airpocket, and finding the "soft spot" on the side of the can and just adding pressure to it. some cans are easier than others...I find coors and keystone very easy.
Also, a fun game kind of thing is called detonator. You and your buddies take a can and slam the side of it on your forehead. After between 5-10 times total, depending on how hard you have done it, the can will explode and break in half. Very fun, but a waste of a beer.