Bad idea, man. That could cost the store a ton of money, create problems for the people working there, distract the police from real emergencies and could get you jail time and a big fine. Also - it's just not very funny.
Instead - try to think of something FUNNY to announce on the PA!
"Attention - (manager's name), please pick up on line 2, you have an emergency call from your girl friend on line 2."
wait 60 seconds...
"Attention - (manager's name), your wife is on line 3, you have a call from your wife on line 3."
wait 60 seconds....
"Attention - (manager's name), You still have an emergency call from your girlfriend on line 2 and a new call on line 4 from your wife's lawyer."
Etc...