Green’s Dictionary of Slang

to hide away, to save up money, to hoard.

1970		E. Thompson Garden of Sand (1981) 343: You sure you ain’t ratholed some for yourself?
1975		J. Wambaugh Choirboys (1976) 63: Lift up your balls. We don’t want you rat-holin twenty bucks in some little crease down there.
1998		D. Jenkins Rude Behavior 336: I was about to run out of names, I did have Cornel Wilde and Gene Tierney rat-holed.