sup m8 is used as a part of the internet lingo and means "suprise mate!". It's a common word used in games or chats, when you dont have time to write. sup m8 is often used similar to hi.
Jack: sup m8, got sum noice memes 4 u
Dan: Hi bro, send em 2 my discord profile, im in game right now.
Dan: Hi bro, send em 2 my discord profile, im in game right now.
by Jay2da_akob July 2, 2018