nacronym
A name that was once made from letters but now it's just a name and people roll their eyes at it because it's too long and silly.
My uncle's name is "LAMBS" but it stands for "Loud Angry Man Brags Silly." Now he just brags and eats meat.
My friend's nickname is "MORON" but it used to be "Mega Outstanding Remarkable Outstanding Nerd." Now he just acts like a moron.
My gym is called "GIRL" but it used to be "Gym Instructors Rock Lives." Now it's just a gym and I don't care.