The Amazing Spider-Man Vol. 1, issue #8, 1963. Flash Thompson threatens to beat Peters ass after school, but a teacher suggests they take the fight to the gym boxing ring instead. Peter is well aware that Flash's head would explode if he hit him full strength. Sam Raimi knew this and apparently took for granted that people in the audience could put it together without him having to spell it out like a children's book from the 60's. It's always been a part of his character.
You gonna stop now or nah?