Mickname 

A person who insists on giving themselves a nickname and enforces its use.

"Hi my name is Michael, but you can call me Maestro" "ok, how did you get that nickname?" " I gave them to myself" "oh, so it's a mickname"

Mickname by Slickgander August 5, 2020

mockname 

A nickname, but intended to mock the person/place/thing.

Tiger Woods now has the mocknames "Lion Woods" and "Cheetah Woods".

When the Browns moved to Baltimore, Ravens fans started calling Cleveland "C-leave-land".

mockname by jevanyn December 14, 2009