(n) a phrase deriving from flash bang, one would use this phrase as a response to a false statement said by another
Because a flash bang is loud and surprising, a false bang should only be used in a situation in which the statement said is barely false, resulting in the false bang being a surprise to the other person
"Why are you on the floor?"
"Cause I fell."
"Wow you're an idiot."
"Don't you mean flash bang?"
"No what you said was false so false bang."