Green’s Dictionary of Slang

to move, to squash up.

1980		R. Heinlein Number of the Beast 476: Show Maureen and Lazarus how we squeeze a passenger into the rear seats; I’ll scootch over.
1987		A. Jones Street Family 171: Scootch over here.
1999		G. Ferguson Shouting at the Sky 51: I scootch up close to the flames.
2005		D. O’Neill Maid’s Friends and Fantasies 137: Now scootch up so your tummy isn’t lying on my legs.
2008		Fredericks & Watkins Fame 72: Kenny plops down next to me, and I scootch over a bit to give him room.
2016		T. Robinson Rough Trade [ebook] Dana and Ginny scootched off to grab whatever they could.