"Happy bday to the dopest girl ever," rapper Tyga captioned his Instagram

By Michele Corriston
Updated August 10, 2015 01:55 PM
Credit: Lilly Lawrence/WireImage

Kylie Jenner is officially all grown up.

Her boyfriend Tyga celebrated her 18th birthday – and entry into adulthood – Monday with a risqué photo of the reality star soaking wet in a curve-hugging dress.

“Happy bday to the dopest girl ever,” the rapper captioned his Instagram.

Tyga, 25, also partied with Kylie and her family at the West Hollywood nightclub Bootsy Bellows on Sunday night, surprising her with an opulent gift: a $320,0000 Ferrari.

Jenner’s birthday will be a week-long affair: She’s set to host a bash at the Beach Club in Montreal, Canada, where she can legally drink alcohol, on Sunday.

The couple began dating in the fall but kept the relationship under wraps until March, when Tyga confirmed Jenner had “captured his heart” on Instagram.