You, Denki and Sero were shopping. You and Denki were pushing each other's butts for fun. As you were standing at the checkout, you thought you'd push Denki with your ass again. So you pushed your butt back, but you felt it wasn't Denki...

You quickly turned around and saw Sero. Sero turned red, and as it turns out, you pushed your ass right into his crotch... He looked away fully red from embarrassment

Denki: Ooo~ he saw this while grabbing a a pack of Chewing Gums