I don't know, nan molla comes from the lyrics of a song called Fake Love made by South-Korean KPOP idol group called BTS. The romanized lyrics of the song say "Why you sad? I don't know, nan molla." If you ask any ARMY or BTS fan why they are sad, they will probably say nan molla.
"Hey you want to grab a coffee?"
"Nah Cherise dragged me out shopping the whole morning, I've got a mallache from another dimension I need to lie down"
or
"Man I have to go buy my girl a birthday present"
"what a mallache!"
Somebody who thinks they know everything and know what they're talking about, when in all actuality, they know absolutely nothing. They tell everyone useless facts that they pulled out of their ass to try and sound smart. There is no convincing them that they are wrong.
Person 1: Did you know that if you eat poison oak leaves, you'll never get poison oak?
Person 2: Um... where the fuck did you hear that..
The antonym of callum, is inclined to punch cunts in the face causing black eyes and broken walls, likely to be found locked inside your nearest shitter with his shirt back-to-front covered in froth and vomit and what appears to be a blown up burrito. Also referred to as MOO.