No cave painting no proof

Used when a picture has been given as proof but you feel you need more proof or you just want to win an argument.

Guy: Dude you are so gay!
You: Bro no I am not.
Guy: Yes, you totally are.
You: No pic no proof!
*Guy presents picture of you having gay sex*
You: That wasn't me!
Guy: Yes it was!
You: No cave painting no proof!
Guy: Damn, I guess it wasn't you.