Funniest is the superlative of funny (and funnier is the comparative). This is not "for lack of one"; "funniest" is the superlative. Funny forms its superlative and comparative according to the standard rule (as in red, redder, reddest and fast, faster, fastest). More @Wikipedia
Hover over any link to get a description of the article. Please note that search keywords are sometimes hidden within the full article and don't appear in the description or title.