Please Excuse My Dear Aunt Sally (order in an equation) My Very Energetic Mother Just Served Us Nine Pizzas (planets) HOMES (Great Lakes) Lefty loosey righty tighty. Still use this one. It even came in handy for college level engineering.
Order of operations: Please excuse my dear Aunt Sally
The Quadratic Equation: In the tune of Pop goes the weasel-- "X is equal to negative B, plus or minus the square root, of B squared minus 4 A C, All over 2 A."
Directions: Never eat sour watermelons
Cranial Nerves: O O O to touch and Feel a Girl's Vagina, So Hot"
This isn't a mnemonic device but it is a trick I learned that I probably use the most as an adult. When I am at a table that is fully set I used to always go for the wrong drink glass. If you put your pointer finger to your thumb on both hands you get a lower case b on the left and d on the right. Your bread is to the left and drink is to the right.
(We read the compass the way we read a book, left to right, and top to bottom. We live in Nova Scotia. So this is how we were taught it in school, haha)
My Very Excellent Mother Just Served Us New Potatoes
Every Good Boy Deserves Fudge
Mary very easily makes John sell used news papers. Damn you, Neil deGrasse Tyson.