Like when to turn off a movie cause they have watched TV for more than their allotted time.
My 4 year old daughter caught me on camera in a silly mood. I hid the remote control in my shirt- hence the very lumpy/ pointy chest area.
Seriously. I had to make a quick decision and it was time for the TV to be turned off. So, turn it off, hide the remote.
What kind of crazy things do you do to convince your kids to change behavior?