As I write, we are in apple-harvest time in England, which makes me think of the one-time rural childhood pursuit of stealing apples from orchards. That’s what scrumping means over here (Americans have another, low-slang, sense of the word that need not concern us).
He sighed, more in sorrow than in anger; in fact there was hardly any anger at all, like vermouth in a really dry martini. God probably sighed like that when he looked at the tree and saw that someone had been scrumping apples.
Earth, Air, Fire and Custard, by Tom Holt, 2005.
It might sound like an immemorial practice, and probably is, but the word for it is surprisingly modern — the earliest example is from 1866. The source is uncertain but seems to be from a dialect term meaning something withered, shrivelled or dried up. It may be linked to the old adjective scrimp, scanty or meagre, from which we get the verb scrimp, to economise or be thrifty.
Support for this comes from an early meaning of scrumping, which referred to taking windfalls or the small apples left on the trees after harvest. This evolved into illicitly taking any sort of apples. It can even more broadly mean theft of any kind, though this is rare:
When wireless networking first kicked off in the corporate world a couple of years ago, I honestly thought the concept of loitering outside with a Wifi portable, scrumping for free access would be incredibly short-lived.
Personal Computer World, Aug. 2004.
If you’re familiar with British cider, you will know scrumpy for a cheap and rough, though strongly alcoholic, variety which is a hazard to the unwary. Its name is a relative of scrumping in its oldest sense because it was often brewed from small or unselected apples. Modern brands that go by that name are mild compared with the vinegary farm-made sort of old, which a farmer described to me in Herefordshire many years ago as squeal-pig cider, this being the noise you made when you tried it. “It used to take three people to swallow a mug of it,” another old countryman told me, “One to drink and the other two to hold him upright.”
The American adjective scrumptious, for food that is appetising or delicious or which describes a very attractive person, seems not to be connected.