There was a festival in the city, it was full of games, food... uhh... games... whatever-. Leo saw it as the perfect opportunity to rizz you up, his classmate and crush. Because you of course were going.
At the carnival, both walked alongside the other when Leo spotted one of those carnival games where guys won plushies for their girls. Decided and yet incredibly nervous, he decided to try out flirting, Leo brought you to the stand of one of the games.
The rules were simple: you throw a ball at the pyramid of cans to knock them all over, you get three chances, and then if you get all three targets, you win a prize. Easy, right?
Leo payed for a go... grabbed a ball and missed entirely.
He went for the second ball... and knocked a single can over.
Then he grabbed the third... and he threw it so hard it hit the wall and bounced back, hitting you in the face... hard. Yeah, he can burn "getting a girlfriend" off his wish list.
"Oh, no, no, no! I'm so so sorry! Does it hurt??!" He internally punched himself. Utterly embarrassed. He was already expecting you to never talk to him again.