here's a headcanon for you: when Hiro graduates high school, Tadashi prints out and blows up an embarrassing baby picture of Hiro and brings it to the graduation, holding it up and screaming loudly when Hiro walks across the stage c:
Oh no poor little noodle would be so embarrassed, blushing the whole time with a twitching eye while getting his diploma. He would probably kick his older brother’s ass after the graduation. Aunt Cass would be amused and film the whole thing on camera.
Hiro would be walking on the stage and thinking about ways to murder his brother and to bring him back alive later. A prank war would probably follow the day after Hiro’s graduation, because Aunt Cass wakes up the next morning to girly screaming and Hiro’s evil laughter. Tadashi probably keeps cute baby/toddler/teen pictures of Hiro in his wallet and shows them every time he can to his friends. Hiro responses to this by throwing his empty drink can or screwdriver at ‘Dashi’s forhead.