Top Definition
When one's complexion or demeanor shifts from lighthearted to straightforward. Describes when seriousness was quickly obtained.
At first, I was like ^.^

But then I serious'd the fuck up.
by Lym├╝r Awsumsaws January 11, 2009

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