Taylor Momsen Turns How Old Today?!

Teen rocker celebrates 18th birthday, but doesn't she already seem so much older?

Happy birthday, Taylor Momsen!

When we heard our favorite former Gossip Girl turned wannabe rock star was celebrating a major milestone today, we assumed she was hitting 21.

After all, this is a girl who flashes her boobs during shows, smokes cigarettes and watches sex tapes.

But hold onto your pasties, because Tay Tay is actually only turning...

The big 1-8 today!

Yes, she's finally a legal adult and she can be as bad she wants to be.

We haven't seen Taylor in a few weeks since her girl-on-girl grinding on stage, but she's got big plans in the next few weeks.

Taylor and her band The Pretty Reckless is hitting Lollapolooza in Chicago next week, before heading to Japan and Australia for more music fests.

The raccoon-eyed singer took to her Twitter to thank fans for their love, saying: "Thanks for all the birthday wishes from around the world...18...big news on the way."

And while she's still got years to go before she can legally drink, at least she can buy her own ciggies now.