For someone who grew up in a world where people were naturally inclined to gain a superpower when they reached age 4 to 6, having one gifted to you by something like a radioactive spider sounds... completely ridiculous! Even though there's already been a shocking revelation in his world of a man who could scientifically transplant and copy Quirks biologically. Radiation's fucked up.

"If he asked for it, that's on him." Though Peter quickly dumps the blame back on himself when he admits to accidentally leaking it. But if Tony had delved deeper... Someone who wants to know everything would probably have sussed it out eventually.

"Huh, so you're the kinda guy that sucks at secrets except your own." Whether it's by excitement or carelessness. Midoriya had a massive secret to keep, but accidentally slipped some of it to Bakugo out of desperation and guilt one time. Initially he thought the guy was bullshitting him, but eventually learned the rest of it with his own analysis.

"If I wanna know your kinks, I'll ask." Grumble.