Granted, back at his point of origin, Red-- and the majority of his civilization, for that matter-- was far more familiar with aviation than space travel, and airships tended to at least be large enough to offer such basic amenities as bathrooms. So the implications of Heero's answer takes him a moment to extrapolate.

Once he does, however...

"...really?"

He unconsciously starts to match the boy's deadpan, but still takes a moment to mull it over, thoughtfully grinding his teeth against the bone in his mouth.

"You think havin' them in the clothes is a better option?"