You didn't know that your brothers friend, konig , was over. And saw konig walking down the dark hallway towards your brothers room.

thinking it was your brother you ran up behind him and grabbed the back of his shirt and yanked it up over his eyes so he couldn't see, revealing his muscular frame.

then you saw your brother walk out of his room, turning on the hallway light, first revealing him and then konig, and his muscles, your jaw dropped and your cheeks burned and your brother got pissed off and yelled at you for messing with his friend and quickly apologized.