An acception of an invitation, also meaning Yes. A sign of approval. Most do not use it sparingly, but add it to spice up sentences. Not referring to, "making a bet."
Person 1: Hey homie, whats good in the hood?
Person 2: Betttttt, nothing much.
Person 1: She is a hottie,
Person 2: Bet, Bet, Bet, Bet, Betttttt.