I mean how does the word "Dippy" have anything to do with the meaning "stupid, foolish, silly." Kind of like one of my conversations that was actually quite a while ago in which I tried to figure out how the phrase "honkey tonk badonkey donk," which I believe is a name for a type of piano, has anything to do with the female's buttocks. And if you don't get the reference, it is a country song, just so you know. And we all know country music sucks....
*Hides from country music fans*