The spead---a method of cheating in which the cheat must have a confederate and a set of signals---is best explained by example. Say the cheat holds a diamond fourflush. He asks his confederate, by signal, whether he has a diamond. If the confederate does have one, the cheat proceeds to get rid of his off-suit card by palming it onto the discards (no doubt while pretending to push the discards to one side) or by copping it with a holdout device. His confederate, meanwhile, will be palming the diamond in his own hand with its face to his skin. At the showdown, the cheat says, "Flush!" He slaps his cards---only four---onto the table face up but in a packet, so that only the top diamond shows. Quickly saying something like, "Seeing is believing," the confederate reaches out to spread the cards. During this move he deposits the palmed fifth diamond onto the poker hand. During his confederate's move, the cheat will probably be reaching dramatically for the pot to help distract attention from the spread.
Although the spread is usually worked with flushes, it can be used to fill a straight or a full house. Watch for it.