Ayt bet
'Ayt bet' is a variant for 'ight bet' which is a variant for 'aight bet' which is also a variant for 'alright bet'
This phrase is used for challenging someone's statement
Example 1

Travis: You can't make that shot

Lamar: Ayt bet

Example 2
Kevin: What do you think about this girl?

Apollo: Nah she's out of your league
Kevin: Ayt bet