A donk bet, or simply donk, is a bet made out of position and is usually small in size. It’s made by a player that has fairly poor poker skills or is not the pre-flop aggressor.
It’s an unorthodox and generally inadvisable betting move, apart from a couple of scenarios. This is why players who make this move are often called “donkeys” or “donks.”
For example, in a No-Limit Texas Hold’em game, the player on the button raises during the pre-flop betting round, and the big blind calls to create a sizable pot of 2,000. Then after the first three cards are dealt, the big blind bets 400, making a donk.