I always just used my left hand with the thumb and pinky as the y and x axes respectively, then the in-between fingers just help me visualize which “point” is higher (we only have two options to choose from if they’re not equal anyways)

I always found these mnemonics just as hard to remember as the actual values so I just draw an isosceles right triangle and an equilateral one. It gives you the values for 30, 45 and 60 degrees.