lol...
I call my brother Hanky Panky... And he calls me Hanky Panky in return. (We got it from the Benny Hill show... (1970s))
We intend to hand over the title to our sons once we're old and incontinent.

My nephew is 10 and my son is 14.
Meanwhile we have a long history of name calling. It just seemed natural.
It's always been like that between us. We're not really close but somehow we find time to hang out... It's weird.
Ummm... What about douche bag?
Also... I often call my daughters boy friend "Champ" because it's one letter away from "Chump". He's an idiot but my daughter likes him.