I know quite well which axis roll, pitch, and yaw rotations are about, and like @ASL_v2.0, I find those illustrations and whatever mnemonic they are trying to reinforce confusing as hell. It should take the average person with good spatial visualization skills about five minutes to remember the distinctions. I still have difficulty with left and right (challenges of being ambidextrous and cross-dominant) but pitch/roll/yaw are quite easy to intuit.
Stranger