Behold; the FlapFlap lamp from Büro für Form. When I was a kid, touristy shops at the seaside would sell empty dog collars with stiff leashes/leads... you'd walk with them as if you had an invisible dog. This is almost as fun.

It'd be even more fun if they sold it paired with an identical lamp with an ordinary cord. Then you could change one for the other while your house guests were in the other room.