At the first stop, he is shown the machine that manufactures baby-bottle nipples. The machine makes a loud hiss-pop noise.
"The hiss is the rubber being injected into the mould," explains the guide. "The popping sound is the needle poking a hole in the end of the nipple."
Later, the tour reaches the part of the factory where condoms are manufactured.
The machine makes a noise: 'Hiss. Hiss. Hiss. Hiss-pop!"
"Wait a minute!" says the man taking the tour, "I understand what the 'hiss, hiss,' is, but what's that 'pop!' every so often?"
The tour guide says, "That's the sound that ensures
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