look up any word, like blumpkin:
 
1.
The face one makes when someone takes a picture of their face up close, or one takes a picture of his/her own self close up, hence "locking in" the face they're going to rock in the picture.

Also see "hot face" and "hot check"
Dude 1: Hey man im gonna take a picture of your face!

Dude 2: Hold on let me lock it in
by Phil Cook November 19, 2007
8 4
 
2.
A strongly affirmative answer to any question.

Has become a common reply from the rise of TV show 'Who Wants to be a Millionaire"
Yeah definitely.. lock it in!
by megdino June 02, 2011
4 2