Device used by protesters to secure themselves to an imobable object and so prevent their removal.
Common examples include a section of drain-pipe with an iron bar through the centre set in concrete.
by bryn July 22, 2003
On the Lock, is the act of getting locked. It is an Irish phrase.

Getting Drunk.
I went on the lock on Saturday night, and thats all I can remember
by Grey Hat Man May 18, 2011
A special gathering or sleepover that takes place in a building from dawn 'till dusk, or 12 hours. At the beginning you're doing a bunch of activities and games, watching the movies the chaperones provide, until usually 9 hours in. And at this time everyone becomes either testy, zombie like, hyper, or bored. Usually the activities cease (except for the video game tournaments and the movies) and everyone falls asleep or just talks about a boring subject. By this time the food is all gone, so everyone is scavenging for any scrap of sugar.
The lock-in started at 7 pm and ended at 7 am. I think I passed out at 4 am.
by TestyWhenHungry April 23, 2011
This game is locked
The test I'm taking tomorrow is such a lock
by ReaganP September 30, 2005
1)to be under really strict, severe obligations or rules
2)to have somebody under control
1) \"Yo,i can\'t go outside man, my parents got me on lock, unda sum really strict shit yo.\"

2)Girlfriend:\"Come here, now!\"
Boyfriend: \"Im coming, sorry i can\'t go right now\"
Boyfriend\'s friend:Damn dawg she got u on lock
by vh_bkbombshell April 27, 2005
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 20, 2007