Mystery Walker - Classroom Management

This is the first year I have done a "mystery walker" and wow! I love it and so do the students! All of my students have a number, so I just put numbers on my chips. Anyway, as you're lining up for transitions out of the room, you grab a number (after I give my box a shake to catch their attention lol) and stick it in your pocket. No one knows (except you) who the "mystery walker" is so everyone must be doing their best job to "win". If the student drawn did excellent in the hallway and line, then they receive some reward. In my class, they get to move their number up on the behavior clip-chart.