The sexual act of shaving your partners head whilst receiving aggressive fellatio and then finishing off by depositing a significant load onto said partner's freshly bald head.

It is important to remember that it only qualifies as a dirty britney if the shaving and the blowjob occur simultaneously and the event is completed with a vast money shot onto the partners head.

A pubic hair piece. A toupee for the pubic area/genitals. In the 1700’s when mercury was used to treat sexually transmitted diseases (Gonorrhea or Syphilis) one of the side effects was the loss of pubic hair. To disguise this condition, that was not cured by mercury, a Merkin was employed.