A Scandinavian drinking game that can be played by two or more players.
Played in a circle the participants hit a beer can against their
head twice with considerable impact (hence duff duff) and then pass the same beer can to their left. The next participant does the same and that continues until the can springs a leak.
The person whose
head caused the leak then needs to open the can and down it.
The
player to the loser'
s left takes a fresh can and the game continues.