The host invited the two Oscar winners, who played mother and daughter in Steel Magnolias, to offer up their favourite swear words on national Tv and after a hesitant start, both actresses let the expletives fly.
Confused Roberts, 46, referenced Field's 1960s Tv show when she asked, "Why am I in a curse-off with the flying nun? How does this happen?"
The Pretty Woman star attempted to keep her swear words family friendly but turned really nasty when comedian Kimmel suggested she was heading for a "massacre" at the hands of foul-mouthed Field, shouting, "Go f**k yourself!"
Prior to the contest, which took place hours after Field unveiled her star of the Hollywood Walk of Fame, she confessed, "I wanna win really bad."
The actresses were each given five seconds to come up with a bad word and much of what the old friends said was bleeped.
Field's foul words included "a**hole", "c**ksucker" and "pr**klicker", while good girl Roberts, who shrieked, "My mother is so proud right now", offered up "d**khead", "s**t-for-brains", "butthole", "tea-bagging", and "son-of-a-b**ch".
Field was named the winner and was presented with a large bar of soap to wash out her filthy mouth.