A slow roll in poker describes an action whereby a player takes an unusually long time to call a bet when they know they’re holding a winner.
For example, a player hits their nut flush on the river on an unpaired board, so they have the nuts. Another player moves all in, and instead of calling immediately, the player with the nuts takes a long time to call and tanks.
By taking his time, the player with the nuts gives the betting player a feeling that they might win in a showdown, especially if the betting player also has a strong flush. This is a natural reaction because, if they had the nuts, they wouldn’t have anything to think about.
The only purpose of a slow roll is to try to upset your opponent and possibly get them on tilt. However, most players frown upon this practice, which is considered very bad poker etiquette, even though it’s not against any official poker rules. In general, you should avoid slow rolling. Learn more about slow rolling in poker.