To cancel someone (usually a celebrity or other well-known figure) means to stop giving support to that person. The act of canceling could entail boycotting an actor's movies or no longer reading or promoting a writer's works.
Did you hear that Celebrity X said this thing about women? Cancelling this misogynistic pig is the just thing to do!
Like noise cancelling, fart cancelling can be performed by cancelling a fart with another fart at the right time. Failing to do so can increase the power of the first fart.
Almost like Netflix ending a really good series on a cliff hanger at season one but instead of a televised series, canceling refers to this act being done a (maybe) not so perfect person’s public career
A sexual act, apparently originating from Gateshead in which a man who does not want his girlfriend to get pregnant but has engaged in unprotected sex with her lets his friend ejaculate inside his girlfriend, which "cancels out" the first man's sperm.
Chavette 1 "Hoy, did ya use a condom?"
Chavette 2 "Nah, ah used "The Cancelling-Out Method" "
Chavette 1 "Good call, ya divvn't want to get pregnant a fourth time"