YUNG BERG IS A CERTIFIED HERB! GETS BEATEN UP & ROBBED @ A HOUSE PARTY IN LA!

Yung Berg -- the guy who rapped on the song "Sexy Can I" -- was violently beaten and robbed at a house in Los Angeles this weekend ... TMZ has learned.

According to law enforcement sources, Berg -- real name Christian Ward -- was at a house party at around 2:00 AM Monday morning when four suspects entered the home and brandished firearms.

We're told the suspects pistol-whipped two people inside the party -- one of whom was Berg. Law enforcement sources say the suspects robbed eight people and made off with $10,000 in cash and jewelry.

A rep for Yung Berg said his client "has been in Vegas." When asked if Yung was in L.A. over the weekend -- the rep said he doesn't know anything about the incident.