Yamato seems completely stymied by that for a few seconds, before he flushes bright red. Because sure, sure, it's true, but he's pretty sure neither of them have ever actually said the b-word before, at least not to each other.

(In fact, he knows he hasn't, because every time he tries he gets caught up in stammering.)

There's a few moments where he seems to be trying to say something, but all that's coming out is incoherent, stammering noises.