When the employees of a restaurant attended a fire safety seminar, they watched a fire official demonstrate the proper way to operate an extinguisher. "Pull the pin like a hand grenade," he explained, "then depress the trigger to release the foam." Later an employee was selected to extinguish a controlled fire in the parking lot. In her nervousness, she forgot to pull the pin. The instructor hinted, "Like a hand grenade, remember?" In a burst of confidence she pulled the pin -- and hurled the extinguisher at the blaze.