If you keep a plastic grocery bag handy, just shake it noisily between both hands it few times. It makes a sound like some predator running fast through leafy woods, and scatters ALL the squirrels and chipmunks. The clever critters are fast learners, though, and I suspect they "catch on" after a few attempts.
That said, chipmunks will do some good by snacking on the grasshoppers in your garden patch from time to time.
The odd part of their grasshopper-protein binge, is that they'll leave the grasshopper "drumsticks" behind.
