A stopper club (German Stopselclub) is a type of social club[1][2] in Bavaria, Germany, the members of which always have to carry a bottle cork or stopper with them.
[3] Whenever two members of a club meet, each can challenge the other to show a stopper.
A member who cannot, possibly having left it at home, has to pay a small fine.
[4] The money collected through these fines is typically used to buy beer at the next club meeting.
Stopper clubs have existed in Bavaria at least since the middle of the twentieth century,[5] and there are currently more than 100.