Definitions by Robert Levine

Knerdle, or knurdle or nerdle or nurdle 

A protuberance, growth or other attachment that should otherwise not be on the item to which it is attached.

"Hey, knock that knerdle off the wall".
or
Remove the inedible knurdle from the end of the banana

Knerdle, or knurdle or nerdle or nurdle by Robert Levine April 15, 2003