Aside from the standard explanations, when I was in yeshivah I heard a jocular explanation that it stands for, going forwards and backwards, in Yiddish:

וויפיל דו וועסט וויסן, קדחת וועסט דו ווערן

"No matter how much you know, you will still be good for nothing."

Aside from the standard explanations, when I was in yeshivah I heard a jocular explanation that it stands for, going forwards and backwards, in Yiddish:

וויפיל דו וועסט קוועטשן, קדחת וועסט דו ווערן

"No matter how much you try to force an explanation, you will still be good for nothing."