Before your gag reflex starts churning up your breakfast, know this: Pools are some of the most disgusting places in the world. It's not the fact they're filled with urine -- they're also filled with trace amounts of feces, bacteria, blood and, if you're hitting up Waterworld, Band-aids. So urine should be the least of your worries, as it's probably the least toxic thing you'll run into in the pool.
Keep moving: The most important thing you need to do is keep yourself mobile. Don't stand still (or sit) and pee like you usually would, because it will become clear you're urinating in the pool right away. Don't close your eyes, don't shake it off, don't start talking to the guy (or girl) next to you. Just take off away from your friends and practice your backstroke for a second.
Use a life preserver: Ladies, a life preserver is essentially a floating toilet -- you should have no problem getting yourself comfortable here, but make sure you release slowly, as you'll likely be detected otherwise.
Don't pee on the water slide: There are a few places you'll get caught if you try to pee -- one is the water slide. Don't pee on the water slide.
Use aerobics as a distraction: If you've really got to go but you can't get away from a group of people, start doing aerobics. This will distract your friends enough that they won't realize you're urinating, and it will also help distribute the urine quickly without calling attention to it. You might be looked at a little weird for the rest of the day, but at least nobody will know you're peeing.
The diving pee: One of the most advanced techniques, the diving pee isn't easy to pull off. You need to be able to start a slow trickle right as you bounce off the diving board, then release as you're falling through the air. If you can pull this off, there is no way you'll ever be caught. It will also add a cool jet stream-looking effect to any pictures taken of your dive.
Tips about the lake: It's no secret a large body of water almost demands to be urinated in. It's just so vast and awe-inspiring, you want to make sure you leave a little bit of yourself behind. We understand, but here's the deal: Peeing in a reservoir requires a bit more finesse, because there aren't any chemicals to counter it. Unlike Mr. Seater, you want to make sure nobody is watching or, even better, make sure you're not peeing in the water supply. If you're already swimming in the water supply for some weird reason, go ahead and pee -- it doesn't really matter at that point. If it's just a big lake in the middle of nowhere, don't worry about it -- urinate as freely and openly as you'd like. But remember, someone on the other side of the lake might be watching. With binoculars. Or a telephoto lens.
If you can't make it to a body of water, just follow the instructions in the video below to pee in public. Summer is hard enough as it is; you might as well make it a bit easier by keeping yourself relieved.