"I solemnly swear they won't turn colour much, even if we wash them! Well, 'cept if ya want them to, of course," Fred tried his best to make the grin a non-faltering one, because Tonks honestly deserved it... and he had to admit he was a bit ashamed of his reaction and the fact that it still was bubbling in his stomach. He was not going to let it come up his throat again that was for sure. On the mention of diapers, though, his eyebrows lifted in a slightly horrified manner, before he furrowed his brows and squinted his eyes in a not too pleased manner, shaking his head a bit, before he actually gave Tonksie a honest to Merlin Weasley grin.
"How'bout we ship those diapers off to Bill or summat? He's gonna need the practice soon enough, I reckon."