Maybe Luke is just really bad at matching his clothing? Or he's always dripping berry juice on it? Either way, black is practical.

"If there are kids around, no, those are just nonsense sounds that you never heard me say." Which implies, that if they are comparatively alone, he most certainly said a string of utterly appalling language. Another lop-sided grin as he shakes out his hand - nearly got it pinched by something. "But, sometimes a bit of technology, advanced or otherwise is a real chuff-sucking leech."