during anal sex, you pull out and the hole is open wide, then you pop your penis back in and again pull it all the way out; this is repeated several times.
A teen or pre-teen girl sucking a boys dick all the way down to hitting the balls- where she may pick up one in her mouth- in oral sex, and the balls are the apple she was going for, so she is bobbing for apples.
'Like- do see that girl over there in that car, look at her go- she is bobbing for apples.'
First used in the story Nevaeh Saga- Marcel Duriez.
When one (male) lies underwater naked in a hot tub such that at least his testicles are submerged, and his partner blindfolds his or herself and attempts to retrieve said testicles with his or her mouth.
Or do this in a public swimming pool to achieve the Orchard Variation.
Also see Bobbing for Assholes.
Dude, I went bobbing for apples last night and am still flossing the pubes out of my teeth.