Top Definition
~Pronounced~
Tac-tic-al -ess-eye

SI is short for 'sick'

If you are tactically sick, you are sick on purpose.

This act was common with the Romans, where they ate a meal, and then threw-up, in order to eat more food.

Nowadays this act is more common in drinking games, where someone is sick to allow more alcohol consumption.
"I needed to Tactical SI to finish that last round up"
by Steven Garfirth August 24, 2008

The Urban Dictionary Mug

Lotsa space for your liquids.

Buy the mug

The Urban Dictionary Mug

Lotsa space for your liquids.

Buy the mug

The Urban Dictionary Mug

Your favorite word on a white mug.

Create a mug

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

The Urban Dictionary T-Shirt

Soft and offensive. Just like you.

Buy the t-shirt

The Urban Dictionary T-Shirt

Smooth, soft, slim fit American Apparel shirt. Custom printed. 100% fine jersey cotton, except for heather grey (90% cotton).

Buy the t-shirt