Boobie Trap - "A trap set to surprise or injure an unsuspecting person." In other words...DANGER! KEEP OUT!
"Leave ignition key with attendant." In other words...DON'T LEAVE ANYTHING OF VALUE IN YOUR VEHICLE IF YOU GET TO WORK LATE AND HAVE TO PARK IN THE AISLE SPOT!
The other words for this window decal would be..."I have a lead foot; please don't give me a ticket, Officer!"