Marginalia

Medieval illustrators (not to exclude clerks, scribes and anyone who had access to paper and had to do a lot of writing and got very bored) put a lot of stuff in the marginalia of their works.

For example, embellishing the capital letters: 

 

Often, it was simply to amuse themselves and offer little jokes for the person receiving it.

 

.......... Ruprecht (For Pete's sake, STOP waving that duck around ...)