It stands for Tiny Meat Gang. This is a group of two celebrities by the names of Cody ko and Noel Miller. If two people are said to be like TMG, it would mean they have chemistry.
Damn, you two are such good friends. Ya'll are like the new TMG.
A drink that is made from Tequila, warm Milk, and Gin. The going rate for this drink is $20 (since most people don't know what to charge -- just give them $20). If someone buys you a TMG is in impolite not to drink it unless you are pregnant.
I was talking to this girl that I really like, but then Kyle bought me a TMG. Since it is impolite to turn down a TMG, I drank it and then threw up all over her. Now she won't return my calls.