honestly i always just look up “baby names” and choose something from those lists
i’d chose a normal name and then the name they actually go by which is like a short version of they front or last name or just a funny nickname
so perhaps they’re called Leonard Smith and then go by Lee
in the movie mid90s they also have some nicknames so for example on is called “fourth grade” because “he isn’t any smarter then a fourth grader” and then another one is called “fuckshit” because he always says fuckshit