1. A
guard hired to protect
strikebreakers; a scab or strikebreaker; a labor spy.
2. One who comes (to the carnival) not to spend but to find cause for
complaint to
police.
3. A
prison guard.
4. A stool pigeon; an
informer. "
You can't get around and promote anything (get stolen food and contraband) in this can (prison). The dump is crummy with finks."
- american underworld dictionary - 1950