These are commonly used internet expressions used to show certain emotions. Instead of explaining how they feel, people will use an expression to represent it. This is also used for emotions that you may feel is something that can only be shown.
This would display happinness.:(
This would display sadness.
This would display a number of things.
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