In the drinking game "Kings," the Thumb Master is the player who is in charge of signalling when someone must drink. At any point during the game, the Thumb Master can put his thumb on the playing surface (table) or forehead. Everyone else must also do this, and the last person that does it has to drink. One is bequeathed this role when he pulls a 10 (or whichever card is deemed). The Thumb Master rules until the next person pulls a 10, in which the new person inherits the title.
I wasn't paying attention when the Thumb Master put his thumb on the table; therefore I had to drink!