This is a typical Chinese slang, which is the initials for “cào nǐ mā bī” which means fuck ur mom’s vagina. Often used in curses for online/real life arguments.
Acronym of the Chinese swear "Cao Ni Ma Bi". Literally it translates to "Fuck Your Mother's Pussy", which means (I) (will)/(want) fuck your mother or I'm your dad.
Unlike the English word of "motherfucker", which suggests incest of the object person, an user of "CNMB" shames others by flaunting itself as a (powerful) rapist/conqueror.
12 step recovery jargon referring to someone new who talks about how great life is, now that they'resober. Usually meaning that the person is out of touch with reality.
The new guy seems pretty happy for a dude who has no job, no money and no family. He must be on a pink cloud.