Ace accidentally locked Luffy inside the car… Which Luffy didn’t even really notice, he was still all happy. In fact, he probably thought it was all a game-

Ace: “IM GONNA BREAK THE WINDOW!! I SWEAR TO GOD IM GONNA BREAK IT!”

Luffy: Giggles

Sabo: Slaps Ace “Don’t break the window! You’ll get glass on him!”