That term is why some refer to folding a hand as mucking your hand  or mucking your cards.  You can also verbally announce fold,  which is a binding comment, and then throw your cards into the muck.

Omaha is a variant of Texas Hold'em Poker. Omaha is considered, by some, to be the hardest game of Poker to master. Of all of the different games of Poker, Omaha is for many the hardest to learn to play and the hardest to bluff in. It is played most often at fixed limits, like Texas Hold'em and pot limit.