Lock

1. An unbeatable hand, a guaranteed winner, or a figurative assertion of such.

Dread Locks

Sports bettors are usually quick to point out that there is no such thing as a "lock" in a sports bet.

Similarly, in Texas Hold 'Em, even a very strong hand (such as a full house) is rarely a true "lock."

Actual "locks" are more likely to show up in games of Stud or Omaha Hi/Lo, where players often have the "lock low" or the "low locked up" before the hand goes to showdown.