Call your own phone.
Save the number, then leave, or hide somewhere in the store.
Call the demo phone back.
It's best to wait, hide behind the DVD's, and let someone really get into trying it out. Then call it.
"Uncle Dick?" you say, or somesuch, after the phone ringing has scared the hell out of them. They'll say, "Uh, no."
"Well is he around there?"
And sure enough, the shopper will ask around for Uncle Dick.
It's amazing how many total strangers will talk to you, and even try to help you.
"Well, there's no employees in this area, can you ask the electronics guy if he knows where the roach killer is?"
And guess what? He knew!
Hours of entertainment. Wish we'd had a video of it.