Originally posted by Jonathan Townsend:
I would suggest using a key. maybe their car key.
House Key. Greater time delay...
Some years ago I suggested to a friend (Toby Wessel) that if he used a key instead of a borrowed ring that he'd find two benefits:
No chance of damaging a customers property
During the drive home they'd be wondering if "their" key would open the front door so when it DID they'd re-experience the magic
He took the idea and worked up a routine that's quite entertaining. You can find it on page 197 of Real World Magic
by Jerry MacGregor.
Toby added a touch that I love. He has the key initialed with a marker... which leads to the thought that he might be using a duplicate key and from there to the spectator wondering if the key is really his...