What if he punched saitama?

Then why does it appear that he struggles when he's holding up a building or bending a steel beam?

why should I care

That's also what science said for Saitama.. It would vaporize you down to a molecular level, then create a black hole. The question is, what if an Oreo punched you?

Science?
Show your work, please.

I probably had it coming anyway.

Saitama just looks Superman like "Dude. What the hell. Now I have to go to hospital and I miss the SALE TOMORROW OH GOD