Joints
Whenever someone complained about being sore or having aching arms or legs, Peter would say:
You know what they say: “If you get stiff in the joints, don’t go in the joints!”
I was always amused, but found that when I repeated this to friends, they just looked puzzled, or thought I was making some kind of sex joke. And I would have to explain that one meaning of “stiff” is “drunk,” and that a “joint” could be a bar, and by the time I explained it the joke wasn’t funny any more.
At least, that’s the meaning I always assumed Peter meant. I could be wrong. Some words have entirely too many meanings.