Bad dog. KA-BOOM!

My sister has one of those "invisible fences" for her dog. The dog wears a collar with a little device in it, and if she crosses the barrier, she gets a mild shock. After the first couple of shocks, she got the point and stopped trying to cross the barrier.

Batman does the same thing with his dog...

...only he doesn't believe in second chances.

From Detective Comics 318, August 1963.