User blog comment:MrCFVanguard/Buddyfight World/@comment-4784241-20140216195616/@comment-6881157-20140218020941

"First of all, I'll say that  funner  (and funnest) are in  Merriam Webster 's dictionary as a word.

Main Entry: fun Function:  adjective  Inflected Form(s): sometimes fun·ner; sometimes fun·nest Date: circa 1846

Normally, if you have a one-syllable adjective like "fun," you add the "er" ending to make a comparative, so "funner" should be correct.

However, fun actually started out as a noun. The adjective use came later. This is why there is disagreement about whether "funner" is correct. Since you can't add "er" to a noun and make a comparative, it seems strange to us.

Still, it is in many dictionaries because many people do use it."

Source:  http://answers.yahoo.com/question/index?qid=20090314142658AAWzRuY