Tyga's birthday was full of surprises Friday night ... he got himself a brand new lawsuit, and it was even hand delivered.
Kylie's BF rolled into Penthouse nightclub in WeHo when a guy popped out of nowhere and served him with legal docs. The process server was unceremoniously and forcibly removed.
As for why Tyga got served ... it could be the Lambo, the Maybach, the Ferrari, jewelry, a home ... who knows?
We're guessing he liked Kylie's birthday presents more.