1)in basketball, to pass to a midair teammate who proceeds to slam dunk the ball. 2)to set up someone else with an easy, quick finsh to a joke.
1) There's Dwyane Wade with the alleyoop to Shaq for the easy finish.
2) "... so apparently me and her are just fuckbudies now"
"what a bitch"
"yeah, fuck her" <---the alleyoop
"occasionally literally" <---the punchline