NMD

Stands for New Member Disorder.

When someone enters your server or group chat and acts like they own the place. Often characterized by berating of current or senior members, or out-of-place criticism in ordinary conversation.

Commonly seen on discord, NMD often occurs when users are invited to servers where they feel they don't fit in.

Yo this new guy PussySlayer69420 has NMD
Yeah we had this one guy on our server who had NMD for a few days but he got better
PussySlayer69420 said "You still use c#? I didn't know this server was for crackheads!" he's got total NMD