"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."
The "!" after the m is a sound made by pressing ones lips together and abruptly opening the mouth, making a popping noise.
The term is an onomatopoeia, used to imitate the sound of abrupt cessation of oral sex.
tony"he put lettuce in his ear"
sam"my book is mongified i dropped acid on it in science"
tony" omg there is only half of it!"