Fun?? Fun??? What is this thing - "fun" - that you mention??? Hmm. Fun. "f.u.n.". Let me go look that up in the dictionary, because if I've ever heard of it I don't recall it.
(OK, imagine Jeopardy music being played while I go look up "fun" in the dictionary. I'll be back in a few seconds.)
OK. I looked it up. I think I get it. In fact, I think I may even remember having something like what was described in Merriam Webster Online a long, long, time ago.
Hmm. Fun. Fun. (Imagine me thinking for a really long time now.) Fun. Fun. un-fay (that's Pig Latin, in case you don't recognize it). Fun. Hmmm. (thinking, thinking, thinking about this thing, "fun".......)
Um. Never mind. Maybe I don't really have an answer about that thing - "fun" - to post here. I actually thought this question was a grammatically incorrect question that asked, "What do you like doing for sun?" Now, sun, I know. I don't see much of it, but I do know what it is. Anyway, never mind.