It looks like Christina Aguilera might have forgotten something when she stepped out Monday night: Her pants!

The “Burlesque” star hit the town in L.A. with boyfriend Matt Rutler in a look that was lacking both pants and, surprisingly, makeup.

Aguilera hasn’t exactly made any Best Dressed lists lately, especially after her Michael Jackson tribute concert wardrobe debacle earlier this month that had everyone buzzing — and definitely not in a good way.

And then there’s her never-ending feud with Kelly Osbourne, who recently slammed the singer on E!’s “Fashion Police.”

Although she wasn’t exactly slinging curse words around this time, Osbourne certainly shared her opinion on the singer’s growing figure.

“She called me fat for years,” Osbourne said Friday. “I was never that fat.”

At least she looks happy.

• popeater