A pearl necklace is when a cock is inbetween two giant titties and are fucking them real hard. When the guys about to cum on your neck, that is called a pearl necklace

see tittie fucking

a woman wraps a pearl necklace around her hand and then proceeds with a well balanced hand job

when someone releases a ginormous jizzload on somebody elses neck.
it is of Afghani origin.

When a male, chunders (ejaculates) onto a girl's neck region, making a pearl necklace.

when you giz on a hot girl's face.

Pearl necklaces or wearing a pearl necklace over regular clothes was a popular code/way for gay men in the club scene to identity “fisties” or other gay men who enjoyed being fisted, specially being at the receiving end of the sexual act. This is where many popular phrases such as “clutching my pearls” came from as this referenced the immense amount of pleasure felt by the fistie, while being fisted. Hence they would “clutch their pearls”. Different colors and sizes of pearls were used to represent specifics, as well as charms on the necklaces. The trend was popular in the underground gay club scene in the 70s and 80s but has since died out.