Naming Kids at Age 18

don't some societies/cultures do this, give a child a placeholder name, and then when they "become an adult/man" they are given a new name?

"Hi, my name is Absolutegeek"

I know some ppl who would be named Shit

"Hello, my name is dragonslayer98"

"Nice to meet you, my name is gayasfuckwejustwantheroutofthehouse."

But what are they called before they turn 18

Or what if you've don't get to have a name but on your 18th birthday you could choose your own?

This made me laugh so hard... garbage xD