funnier mean more fun but its a better word to use and it makes more scene to use instead of saying ..."oh that picture is more fun" you can say oh that picture looks funnier"
OMG... that picture is funnier than that other one...
Him: Kidd twin 1 is funnier than Kidd twin 2.
Her: That doesn't make sense. Haha. Kidd twin 2 is the funniest.
Him: You know I'm right. Funnier sounds better and Kidd twin 1 is!