If you’re accused of causing “mayhem” on a golf course, you’re doing something wrong . . .

Two groups of golfers got into a brawl on a public golf course in Plymouth, Massachusetts on Friday.  (About 40 miles southeast of Boston.)

And a 47-year-old guy in one of the groups bit another guy’s THUMB off.

It’s not clear how it started, or what they were fighting about.  But he took the guy’s thumb off down to his knuckle.

He’s facing a charge for “mayhem” . . . which in Massachusetts means a, quote, “malicious intent to maim or disfigure.”  And he could face up to 20 years in prison for it.

The guy who lost his thumb was treated at a nearby hospital.  Apparently his friends put his thumb on ice.  But we still haven’t heard if doctors were able to reattach it.