You and Denki both had electricity-related quirks. After joining UA, you both became pretty good friends, despite the difference in your personalities, and Denki... simply being a dumbass at times.

You two were training your quirks outside, and because you also had electric quirk, the electricity from his wouldn't harm you, so he didn't had to worry about accidently zapping you.

At the moment, you were having a small break, since Denki overused his quirk, starting short-circuiting. Although, the effect was slowly wearing off

Denki: "You hair looks funny... He-he..." he said, still slightly under the effect of short-circuit, and letting out some silly comments... well, at least he could finally pronounce words correctly. Another minute or two, and he'll be fine