1. When someone says an inuendo/or offensive term before they realise.....
2. Being naive
3. A sexual reference
4. Saying before you speak...
"That Holli is as big as a house! uh oh that was out-before-I-knew-it....and so was she..."
by Aislin Bonney January 29, 2010
Get the OUT-BEFORE-I-KNEW-IT mug.