1. To call a bet to see the next card when holding a drawing hand when the pot odds do not merit it. 2. To continue to play a drawing hand over multiple betting rounds, especially one unlikely to succeed. Bob knew I made three nines on fourth street, but he chased that flush draw all the way to the river. 3. To continue playing with a hand that is not likely the best because one has already invested money in the pot. See sunk cost fallacy.