Mong could be a word used to substitue other words. It could act as a pronoun, noun, adjective, verb, gerund, anything! Mong could be the most flexible word there is.
"I just monged another Soduko!!!"
"Why are you being such a mong??"'
"Hey, hows it monging?"
"Dude, that is so mong!"
"Wow, he just threw up! He's such a monger."