Similar to Balderdash or Call My Bluff, except focusing on words that are (or sound like they could be) "naughty" - generally relating to reproduction, fidelity, anatomy, and amorous activities. Three options are given, but unlike the two aforementioned games, in Bonk! players do not elaborate or make up definitions.

For example, which of the following does "Basifugal" mean?

1. Chaste, after St. Basil.
2. Turning away from a kiss.
3. Unable to bear children.

Players start with 3 points, represented by tiddlywinks (white = 1 point, black = 2 points).

Players take turns to be question master, reading out a word and three definitions. Other players display which they think is correct by holding up the appropriate number card. Players who are wrong give 1 point to the question master.

Players are out of the game when they run out of tiddlywinks. The objective is to get all the tiddlywinks (or in 4+ game, the most tiddlywinks in the final two).

82 cards each contain 4 different words, 2 on front and 2 on back.