Fap block
Stopping a person from masturbating, when they either want to or were in the middle of the act, by simply being present. Similar to a cock block.
Guy 1: "Dude I caught my brother with his pants down looking at his desktop... It was weird"
Guy 2: "Aww man, not cool, you totally fap blocked him."
Guy 2: "Aww man, not cool, you totally fap blocked him."