The teachers had been going through strategies that different heroes used to interrogate villains or suspects. One was a lie detector. You were a very private guy and usually stood in the background. You hadn't even raised your hand but you were volunteered to be the one strapped to the lie detector. Meanwhile Denki was just chaotic, Lida was lecturing and focusing on the task, Mina wanted juicy details, Mineta was being a perv, etc.