Killer never saw it coming.

They were probably arguing about something trivial and kidd's thinking - blues i hate his stupid pretty face. He's so smug when he thinks he's right. I'll show him!

Kidd just learned a new way to win; poor Killer's going to need some time to figure out how to counter this.

[The secret reason he wears a mask - it's the only way to stop kidd XD]

... But killer also wins because now anytime he needs to distract kidd he can just start a petty argument and goad kidd into kissing him to shut him up ^^;

They both think they are being very clever