When employees of the restaurant where I work attended a fire-safety seminar, we 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.
Our instructor hinted, "Like a hand grenade, remember?"
In a burst of confidence, she pulled the pin—and hurled the extinguisher at the blaze.