A spit-in is a form of nonviolent protest in which one party refuses to swallow another party's ejaculate, often to promote change in the relationship, or simply out of spite.
"Yo fellow human, total bummer. My wife's staging a spit-in. I think she's trying to get a bigger allowance. I'm inclined to acquiesce."
"My boyfriend won't gargle my G-juice anymore mom. I bet this is because I puked on his dog."