Drum can

The Drum Can (as it's referred to in-game) is the Guns Of The Patriots equivalent of the Cardboard Box used in previous games. Solid Snake uses it to hide from the patrolling guards, and can push it onto it's side and roll into a number of guards to knock them over. However, doing this too much can make Snake feel sick. In the E3 2007 gameplay demo, snake threw up upon ousting 2 guards with the drum can barrel roll.

During the first gameplay video feature, Hideo Kojima comments that the drum can provides more protection for Solid Snake, and has the ability to deflect bullets.