Why we have nicknames like this ?

Hello guys how you doing ? today i passed a weird and embarrassing moment in my life

i was waiting for a verification in a line, the employee was calling nicknames to mention our turns, it's my turn and he asked to me to wait in a place in front of the line, suddenly he called someone "MR. LMA9LI", and in this moment, i could't breathe, and i was struggling to not laugh, all the line was looking me

why there is grandparents in this land can call themselves like that LOL ?