at least when I was a kid I used to laugh at words like "potato", "pun" and "banana". I don't have a good point though, potato just sounds really retarded, "pun" sounds the same as "pum" that is "fart" in my main language and banana itself is funny to kids.
Also "potato" in my language is "batata" that coincidentally sounds retarded too
In japanese I laugh at "kikasete" (I don't know the spelling), if I recall correctly it means "listen up", because it sounds like "what a cock" in my language.