"Uh..." Peter falters a second because that was a bit of a rough year for him and he really didn't want to go into too much detail. That wasn't what Cap meant anyways though so he opts for the short version of event.

well, short if you're Peter Parker.

"Um-a cursed fieldstrip to Oscorp, a radioactive spider-bite that caused some really weird and traumatic genetic mutations-not that I'm traumatized over it. A very expensive trip to the ER-honestly, I think the bill was more truamatizing then the spider-bite-but anyways-now I can do this!" He uses his powers to stick of the notebook he'd come back for and then tips it over to show off his powers. "That's not all I can do though-I also have super strength and a healing factor."