Best definition
zyooom
Zyooom is a sexual action in which the male immediately ejaculates as soon as his penis is inserted. Basically just

Instantaneous ejaculation. Often derogatory as the Os represent each inch of the male’s penis and it implies one cannot last long in bed.

Guy 1: Damn her pussy strong af

Guy 2: Did you Zyooom?

Guy 1: Fuck Off cunt