A classic example of how to check trap someone is when you are acting first on each round of betting and you believe your opponent is on a draw. If on the river, you think that they have missed their draw and you have a made hand such as top pair, check here to allow your opponent a chance to bluff at the pot.

This sounds obvious but a lot of players get set in a mode of always betting at the end if they think that they have the best hand. In most cases you should but in this case what can your opponent call you with? Checking to the player who has missed their draw also conveys weakness in your own hand as if you were on a draw yourself giving your opponent more incentive to steal the pot often with a big bet to protect the money they have already invested in their draw. Call and take down a nice big pot.