A friend or colleague whose foolish mistake has ruined yours or someone else's plans... The metaphor represents both the accidental nature of the mistake or splash, and the sticky mess of events which the mistake causes.
Use: Beration, ridicule, declamation of responsibility, winding up your clumsy friends.
Noun, very improper.
"Ahh lol you got a Jizz Splash on my nose"
"You Jizz Splash!" On hearing that your friend forgot the mayonaise/ got the address of the party wrong/ used your lubricant as hair gel/ broke your bicycle/ burnt the toast/ lost your dog.