I heard the dirty mnemonic but it was in whispers from other students.
As often the case, @pulykamell could be my spokesperson. I’ll add that the prefix of brown black, super common at least when I was in school, (brown blk red = 1k, brn blk org = 10k) to mean 1 & 0 makes it very easy to remember that ROYGBIV starts at 2.
1 is Brown Black, because that’s the one you see all the time.
1.2 is Brown Red, because that’s the next most common, and the one you use when Brown Black was a little too small when used in circuit.
So you know Red Red is 22, and Orange Orange must be 33, because that’s the only double number.
If it matters, the only other thing with Red in the second position is 82, anything else starting in Orange must be 39, starting in Red must be 27, 47 is Yellow something, (because Red, Orange, Yellow) which leave you 56 and 68. 56 is that odd one with the odd numbers, and you never use 68. 15 and 18 give you a little trouble, but at least you know that they are 15 or 18.
Never had to worry about 10% values: 20% values always got you close enough (even when using 10% resistors)
Anyway: 10,12,15,18,22,27,33,39, 47,56,68,100. If you remember those numbers and a few colors, you can get the rest. And you don’t have to remember the numbers very well, because they go up (and down) by about 20%. 33 … 47 --> yeah, the one inbetween is 39.
It’s all 1% and better now, but they aren’t colored anyway.
I think the numbers go according to the Series of Preferred Numbers.
Better identification of little ceramic capacitors would be great. A lot more of them have decent markings now but in the past they often had cryptic little codes for different values. One distributor gave me a cheat sheet long ago after I lost my capacitance meter (stolen I’m sure), but there were always some turning up with something new or no markings at all.
As soon as I saw this OP I thought, yeah this originated with guys who were trained by the military, probably in the World War II era. Science teachers of all stripes would have overlapped considerably with that demographic in the 1970s.