More specifically, girls between the ages of puberty and menopause who are not on a type of birth control that completely gets rid of your period.
Everyone else: consider yourself warned.
Several months ago, I discovered one of the greatest things ever--the menstrual cup. A menstrual cup is a small silicone cup that replaces tampons and pads during your period. The Wikipedia article does a good job explaining what it is/does but truthfully I got way more information by going to this LiveJournal community. There's nothing like first-hand advice from other women!
The cups come in many different shapes and sizes so I recommend doing a lot of research, and you may need to purchase a couple before finding one that fits you right but the time and cost is WELL worth it! You can read all the official information out there via Google and find how-to videos on YouTube so I'm just going to give you my first-hand info.
Based on various data, I knew in advance that I am much smaller than average so I bought the smallest cup I could find, even though I'm over 25/30. It took a few tries before I found a folding technique that worked and was able to get it positioned correctly. Then I woke up the next morning completely terrified because I couldn't reach it and didn't know how to get it out.
I read several more entries at the LJ community and decided to try it in the shower. I definitely recommend this especially the first few times. (Go to the bathroom first because you will be putting a lot of pressure on those muscles.) Sit in the bottom of the bathtub with the shower on, legs out like a frog, and bear down as if you're going to the bathroom. It should only take one or two hard pushes to get the cup in reach. Then you can hold the stem while you get your breath and push again. It really doesn't take long to get it down where you can reach the bottom of the cup and push/pull it out.
It will spill blood out but the water will just wash it all down the drain. Rinse the cup out and re-insert using one of the fold methods. (YouTube is great for learning all the folding methods--I like the 7-fold.)
It took me a few times before I tried it sitting on the toilet and so far I've only dropped it in once. Thankfully it was at home and I had time to boil it before re-inserting.
On average, the cup only has to be emptied 2x a day so it's pretty easy to schedule it for a convenient time. If you're away from home, though, try to use restrooms that don't have stalls, like hotel lobbies or the 'family' restroom at malls and airports. If you have to use a stall, take a bottle of water in with you to rinse out the cup.
It's ok to just rinse with regular water during your period, but between periods you can clean it with alcohol or boil it. If you boil it, hold it by the stem w/ tongs so it doesn't touch the sides/bottom of the pan or it will melt.
Why do I love this thing? For one, I never have to buy tampons or pads again. Or worry about not having them on hand when I need them. The cup can even be inserted before you actually start your period so no more 'oops'.
And I feel like I have really put it to the test....
One month in the summer, on the first two days (heaviest flow, worst cramps) of my period, I rode my bike to the Y, worked out for 2+ hours, and rode my bike home. The next morning, I went back to the Y and worked out for about 4 hours, including water classes. I had no discomfort (even on the bike), no odor while sweating profusely, and no worries when I changed into my swimsuit and jumped in the pool.
A few months later, I started the day before my sister's wedding. I ran errands all day, spent the afternoon with her, and the evening baking pies for the reception. Then the day of the wedding, helping everyone get where they were supposed to be, etc. All that with no concerns about leaking, or making sure there was a bathroom and a tampon handy every few hours.
If you have any questions, PLEASE ask! If you don't want to leave a public comment, send me a private message via email or facebook or whatever! I love this thing and want everyone to try it!