Lindsay Lohan turned 23 years of age this weekend and to celebrate it, she regaled us with a partial nipple slip.

The auburn-haired actress is back in the continental US after an extended vacation in Hawaii, and she chose Vegas' first-ever ultra pool Wet Republic as the location to commemorate her birthday.

Lindsay partied all day yesterday with friends (Samantha Ronson was not among them) in a celebration that began early in the morning and went way into the night. As a result we got a partial Lindsay Lohan nipple slip and some great bikini pictures.