Jamie Lynn Spears JLSPEARSCASEYALRIDGE_01.jpg Uh-oh - sounds like Jamie-Lynn's been getting rowdy while her mother Lynne's away taking care of Britney!

The Star is reporting that last Sunday, while Lynne was in LA looking after Britney, Jamie Lynn was at home in Kentwood throwing an unsupervised Super Bowl party with a bunch of college students!

Sources say that "five college age women" arrived at Lynne Spears' Kentwood mansion in "a Jeep SUV with Ole Miss University and Delta Delta Delta sorority decals on the back window" in the middle of the afternoon on Sunday.

“They were all laughing. They looked really happy and excited to be at the house, like they hadn't seen Jamie Lynn in a while,” a witness told the Star.

Of course, that wasn't the only suspicious activity seen going on at the Spears household yesterday. Earlier in the day, witnesses may have caught the pregnant teen sneaking across the Louisiana border - to buy alcohol!

Spears was spotted (in a baggy, baby-bump-concealing sweatshirt) at a Wal-Mart SuperCenter in McComb, Mississippi with boyfriend Casey Aldridge - instead of patronizing the much-closer SuperCenter in Amite, Louisiana.

The difference? According to one source's speculation, the McComb store sells alcohol on Sundays! "Maybe one of them has a fake ID," the source said.

We just hope that if Jamie Lynn did buy any illicit booze, she bought it for her guests - after all, drinking's bad news for either teenagers or pregnant women!