49ers Field Crasher Was Arrested

The guy who invaded the field during the 49ers vs. Rams game last night -- and covered more ground than Case Keenum -- was arrested immediately following his 4th quarter romp.

The invasion actually went viral, thanks to the brilliant live commentary of MNF announcer Kevin Harlan ... who proclaimed, "The guy is drunk, but there he goes!"

He later described the incident as, "The most exciting thing to happen tonight."

It was.

But it came at a cost for the invader -- who happened to be an underage male ... according to the Santa Clara PD.

A police spokesperson confirms the kid was arrested for an unspecified misdemeanor.

More importantly ... maybe the Rams should give him a tryout.