This is the $10 Das Can-In-Stein available from ThinkGeek. It turns any 12-ounce can into a stein. It was an April Fool's product that they made a reality. They're not actually made out of metal though, they're resin, but will probably still make a formidable weapon in the event of a bar fight. Especially with a full beer. Just swing that f***er at an enemy's temple and ca-crack! PROPTIP: If that doesn't knock them out they're probably gonna want to kill you so be ready to counter with a sock full of quarters.
Keep going for a couple more shots and a video.
Thanks to Garen, who drinks out of red plastic cups like a normal college student on a budget.