First post and explanation
So here's the latest way I've confused my host family: it was after dinner and my host mother had set out a plate of grapes for dessert. The grapes that my family eats are extremely small and somewhat sour, reminiscent of blueberries in size and taste, but my family tells me that American-style supersized grapes are sold this side of the pond too. So anyway, my host father was popping grapes, chewing them for a few seconds, and then plucking the grape skins out of his mouth and setting them on his plate. I just figured he was fussy about his grapes. For my part, I ate them skin and all, what I had assumed was the normal way.
My host father looked in confusion between me, my empty plate, and the bits of grape vine left behind from the grapes I'd just plucked. Then he asked with total incredulity, "You eat grape skins?"
"Uh... yeah. Why, is that strange?"
"I didn't even know they were edible!"
"Oh, yeah, they're nice. I like them."
Which is true, I do like grape skins. They add a crisp texture to the taste.
"Do all Americans eat grape skins?"
"Well, not all, but generally yeah, Americans eat the skins too. It would probably be considered a little rude to take the skin out of your mouth and set it on your plate."
My host father and host sister, all the while eyeing me with suspicion, then tried this crazy barbarian custom themselves. They judged it "really weird" and continued the way they had before with their civilized, unskinned grapes. I shrugged.
Wait, now that I think about it, do the Japanese shrug? I can't remember ever having seen a Japanese person shrug to communicate feelings of "eh, whatever." Maybe my host family thought I was starting to develop a shoulder tick on account of my barbarian grapeskin-eating habits.
Germany had absolutely nothing on this country for strange surprises. Every time I accustom myself to one layer of differences between Japan and home, another layer surfaces. It's intricate and alternately amusing or frustrating, depending on how stressed I am.