Justin Bieber Unloads His Pet Hamster On Screaming Fan

Justin Bieber isn't gonna win pet owner of the year any time soon, because we found out he just dumped his pet hamster on an unsuspecting fan.

We got grainy footage shot Wednesday night after Jingle Ball at the Philips Arena -- showing Bieber walking up to a group of screaming fans and signing autographs. Then, suddenly, he handed his hamster cage to a girl in the crowd, declaring, "That's all you."

It's hard to make out much more because of all the screaming, but you can clearly hear Justin tell the girl, "You gotta take care of PAC."

The girl screams back, "I WILL TAKE CARE OF HIM!"

Funny ... PAC the hamster has his own Twitter account -- with over 40,000 followers -- and his last tweet was on Wednesday ... "ATL this is gonna be fun."

Poor guy never saw it comin' ...