The act during sexual intercourse, when right bfore the male climax he pulls out just before ejaculation. Proceeding to defocate on his partners face and then ejaculate on the feces. Therfor covering the shit with semen looking like a birthday cake or a plethora of other things.
Person 1 = "Hey man totally pulled a fake out when i birthday bashed Lindsey!"
(Adj.) A personal description related to the whorish or slutty acts willing to be performed for one's partner only on their birthday, birthday-only acts being more extreme than everyday acts.
1. Your mom is beyond nasty - she's birthday dirty. She frightened me a little last night...
2. My ex was a little drunk last night, so I figured why not get birthday dirty for a little while...