Kerst is that act of writing your name on a woman during sexual intercourse and drawing an arrow to where your penis is inserted
Kerst is also a term expressed once you have reached a climax of heterosexual intercourse in the mouth (blowjob)
"So I here you kerst that bitch last night"
"Hey, Ho! How much for a kerst?"
"Um... Excuse me Officer, that man over there kerst me last night"
"So your saying he screamed out kerst?"
"No nigga, he wrote his name all over my back...therefore he kerst me"
"Bitch please, I've kerst you before, see...right there!"