The hot mama, who turns 29 today, was celebrating South of the Border in a bikini bottom and not much else. She was joined by famous friends Christina Aguilera and Sam Ronson in Cabo, and she may have been celebrating more than just her birthday...
While having dinner at a local restaurant, Nic was spotted wearing a "bride-to-be" sash and necklace adorned with plastic penises.
Was this trip also a bachelorette party?
Nicole's rep didn't respond to our request for comment on what exactly she was celebrating, but either way, happy birthday!
Nice to see the former wild child is staying out of trouble but can still cut loose!
See more stars on their big day in our Celebrity Birthday Bashes gallery!