I grew up with the word “hand muff,” a cozy fluffy tube to keep hands warm in winter.

Nowadays whenever someone says “muff,” someone else giggles 🙄
I grew up with the word “hand muff,” a cozy fluffy tube to keep hands warm in winter.

Nowadays whenever someone says “muff,” someone else giggles 🙄
I think that’s your why. As to when, no idea. I first heard people talk about “eating muff” or “muff diving” going back at least 25 years, but I’m sure it’s probably much older than that.
I’m pretty sure I heard the term “muff diving” in high school in the 1970s.