I learned it in Geography

In the department of 'be careful what you wish for' it occurs to me that there's a way that this could happen in the manga. Saitama has never seen what Genos is like away from his side. One thing that pleasantly surprised me was seeing Genos blossom into a smart, capable, and thoroughly emotionally-attuned person when it came to working with other heroes. It's a real talent to work out where you need to be to be effective when working with others, in front, behind, beside, or out of the way altogether. Genos showed he could do this and make it look natural. The way he supported Tatsumaki so she could achieve multiple objectives without compromising on any one of them was the best. I don't think I'm going too far when I say that were Genos to have been dispatched with Tatsumaki, City P would probably still be standing. She had to destroy the city because she had no way of scanning for any remaining monsters, which is something Genos can do, and she trusts him to be thorough.

Something Saitama wants deeply is to be able to work with others to achieve something bigger than himself. Even with the Hero Name Victim Association, he knows he's carrying them. Should he get to see Genos working with another hero to do more than either could alone, I warrant his face will change, and not in a good way. It's true he has times he's envied Genos, but it's never been a problem. This would challenge Saitama as nothing has before. Working well with others is one thing Saitama can't rationalise as coming out of an upgrade. Besides envy, there's also the real possibility of jealousy -- why can't he be like this for me!? All sorts of interesting and ugly feelings he'll have to confront.

Dylan of @acetooney is a Lawyer IRL and he actually pulled this in court! And just like Phoenix here, he made the Judge laugh and got away with it!

Bonus wtf points for somehow rotating through ninety degrees by the end of the scene into the bargain:

The full body is never seen in the movie, but it’s still cannon that it looks like this

Source:

Antonio de Garay, Antonio de Garay Arquitectos Asociados.