While I don't normally drink beer from aluminium, and I'm not really a fan of skulling beer, there is a fine Australian technique I feel it is my duty to impart at this juncture.

If all you have is a tinny and a sharp object, carefully use the sharp object to pierce the bottom of the can.
Tilt your head back and hold the inverted can above your mouth.
Open the can and suck it down.

Try doing that thirty times after a bottle of cheap ouzo and surviving ......