To be in agreement with someone. It can be used in place of the word "Yes". A short version of 10-4. Can be used by raising your four fingers at someone.
(John) Lets get out of this place and grab a few brews. (Tibbs) "Four"
The Urban Dictionary Mug
One side has the word, one side has the definition. Microwave and dishwasher safe. Lotsa space for your liquids.
Buy the mug