This is by far the easiest, and therefore most dangerous, manner to cheat. It is virtually impossible to catch players in collusion, and even more difficult to prove it.

The danger of collusion can not be emphasized enough. Collusion requires minimal skill and minimal preparation, but poses a great danger to the honest players at the table.

Collusion involves any number of players (usually two) silently working together at the table. Working together, these players can perform the following maneuvers:
 

• one uses a hand signal to identify the strength of his or her hand

• one distracts the others at the table while the other manipulates the deck

• Signals are exchanged to carry through a betting scheme.

• All profits between the two are divided evenly and privately in the end.

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• One quickly flashes their hand for the other to see. One manner of performing this works as follows. After the deal of a Draw game, for example, one player picks up their cards from the far side of them. Doing so quickly exposes them to any player who is looking at the perfect moment.

• The partners speak to each other in a language not understood by the rest of the table. This is likely more prevalent in private games and casino games than home games.

• Sandwiching: This is the tactic used when two colluders remain at the table with a third player. Under the assumption that the two colluders will be splitting all profits after the game, it benefits them to continually bet back and forth ("sandwiching" the third player), forcing the third player to either see all bets or fold. As long as the colluders are betting maximum, they will most likely intimidate the third player out of the game.
   

Collusion is used to describe any cooperation between two or more players, for the purposes of: pooling and splitting money after the game, revealing any of their cards to each other, using table talk, using gestures as signals, using betting schemes, etc.



This "Rounders"-like activity is most prevalent when two strangers have joined the game, or if one acquaintance has introduced a stranger to play at the table.