Hiccup wasn't the type to pry but the word itself was hilarious to him.

"'Muggle.' What - what kind of word - that is the most ridiculous word. What do you call yourselves? They call magical wise women and wise men seiðr, in the stories where I'm from - not that magic is real there. Which is an actual respectable name." He laughed. "Muggle. That sounds like a breed of dog."

He seemed amused rather than offended, though.