When playing basketball, they way someone sticks out their booty really exaggerated when dribbling, in triple threat, or about to shoot. Their back is arched backwards too far and their knees are low and wide apart. Looks like they're about to booty dance. Mostly, and hopefully, found in females.
A baseball booty is a baseball players butt when he's in his uniform. Most baseball booties are kind of perky and big but they don't look like a girl butt. Baseball booties are awesome, but not every player has one (at least not a good one)