a cut of lamb, mutton, or pork meat taken from between the loin and hindleg, esp of a lamb, mutton, or pork carcass
informal a fool; a stupid person
Chumps always make the best husbands. When you marry, Sally, grab a chump — P G Wodehouse
off one's chump
Brit, slang crazy; mad
[perhaps blend of chunk and lump1]