Kinda Like a Zoo

TAKE-OUT-TIME-OUT is a portable "time-out" mat. The "time-out" method is the most common and successful of methods used to manage child behavior (ages 2-8), even more successful when using a consistent spot. TAKE-OUT-TIME-OUT can be used anywhere anytime (home, store, restaurant, playground, etc.).

Link.

Advertise to everyone that the kid is being punished, but don't spank him in private.