"No johns" means that you can't make excuses. It is the perfect counter argument to anyone who is making any type of excuse whatever. When someone makes excuses or tries to make excuses, they are "johning". If this occurs, tell them "NO JOHHNZZ".
Me: "Dude, I just 4 stocked your Marth with my Pikachu.
n00b: "Yeah, but Marth isn't my main character."
Me (as well as crowd): "NO JOHHNZZ SON"
"That was definitely East Coast DI."
~ Commentator (East Coast)
"What's wrong with our DI?"
~ Mango (West Coast)
"Your DI is horrible. Trust me. Your DI causes you to die."
"Our DI rapes. We like to have fun, so we let let each other combo each other. That's how it works. We're not super-serious like you guys."
"Alright. In the East Coast, we got this saying called 'No Johns'."
Revival of Melee 1 Crew Battle Commentary