Slow roll
A slow roll is when a player who knows they have the winning hand deliberately stalls before revealing it at showdown, falsely letting the opponent think they won.
A slow roll happens at showdown, after all the betting is done and players turn over their cards. Instead of promptly showing a hand they know is best, the player pauses, hesitates, or even acts disappointed, letting the opponent believe they've won for a beat before flipping over the winner. It's considered one of the rudest moves in poker because it offers a false moment of hope purely to rub in the result.
It usually comes up at the river, when only two players are left and one is sitting on a monster like the nuts. A quick, clean reveal is the polite norm; dragging it out to savor the other player's reaction is what crosses the line. Slow rolling isn't against the rules the way angle shooting can be, but it breaks table etiquette and tends to sour the mood fast, even in a friendly chip-only game.
As a beginner, the simple habit is to show your hand promptly when you know you've won, or muck quickly when you've lost. There's no strategic upside to a slow roll, it just makes opponents dislike playing with you. Don't confuse it with normal, honest tanking earlier in the hand, where you're genuinely deciding whether to bet, call, or fold; a slow roll is specifically delaying a known winner at the very end.
Example
You hold A-A and the board reads A-K-7-2-9, giving you top set, the clear best hand. Your opponent excitedly turns over K-K for a set of kings, and instead of showing right away you sigh, stare at the board for ten seconds, then slowly flip over your aces; that long, theatrical pause before revealing the winner is the slow roll.