As a topologist (or, perhaps more accurately - somebody who has taken primarily topology courses recently), I see tori (donuts) all the time. And people always talk about a meridian circle on a torus, versus latitudes. I generally have a hard time remembering which is which. But recently I decided a fun way to remember it by thinking about donuts.

Your first bite into a donut, unless you're doing something wrong, is essentially along a meridian. That works out well for remembering things, because your first bite should also be accompanied by an 'mmmm', and 'mmmm' starts 'mmmmeridian'.