Clark was called "lack of attention", "can't focus on something important enough" a few times by Bruce because he's too busy staring at his tempting boyfriend. It's not Clark's fault for getting attracted to Bruce, to his voice, his body language, nor his batsuit ears. Clark was fine with that, but one day he felt like challenging Bruce about concentration. Bruce was confident enough he would win.
Until it came to the challenge: Clark would explain a certain history about Kryptonian while fucking Bruce's brain out, and Bruce must tell what Clark had said. Clark explained it nicely and slowly, like a good storyteller, so Bruce could hear it all pretty clearly. It's a long story, and they would done fucking after Bruce told what he heard. Clark won and he got the reward to cuddle his spent bat.
