To steal fruit, especially apples, from a garden or orchard.
1994, Edward Bond, Edward Bond Letters, volume 1, page 180:
(we've all seen trees, and arent Adam and Eve condemned for having gone scrumping?; interestingly a great philosopher recalled Saint Augustine spent a lot of his long life being racked with guilt for having gone scrumping for some pears when he was a boy! ...)
1997, Caradog Prichard, translated by Philip Mitchell, One Moonlit Night, page 18:
[I]t was something that every schoolboy of my generation almost `had' to do, as obligatory a proof of impending manliness as scrumping apples or pulling girls' pigtails. I told myself I'd never scrump gooseberries again, or go scrumping apples with Huw and Moi ...
2006, Richard Dawkins, chapter 7, in The God Delusion, Boston: Houghton Mifflin, →ISBN, page 251:
Scrumping itself is a mot juste of unusual economy. It doesn’t just mean stealing: it specifically means stealing apples and only apples.