The word "schnickelfritz" is a term of endearment of uncertain Germanic origin. It means
something akin to 'rascal', 'scamp', or 'little chatterbox'. The word is usually used with children, but can also be used between others who are close with each other.
Also, Schnickel Fritz is a folklore character. Fritz was a rascally
little boy. He also is mentioned in the
Schnitzelbank song. (Google the song...I'm not chronicling it here.)