I distinctly remember that Seinfeld episode where Elaine talked (incessantly) about who was, and wasn’t, “spongeworthy”. Turns out the “sponge” in question really exists:
It was made famous in the 1995 episode of Seinfeld when Elaine stockpiled it for boyfriends deemed “spongeworthy”—and now, the contraceptive sponge is set to return to store shelves in the U.S. Introduced in 1983, the Today Sponge, a spermicide-coated polyurethane barrier placed in the vagina to inhibit sperm, was once the most popular over-the-counter birth control for women. It was removed from pharmacies in 1994 after manufacturing problems, then reintroduced in 2005 under new ownership. After the new owner went bankrupt in 2007, the Today Sponge went out of production. Repackaged for a younger generation, it will be sold by a new distributor as of this weekend. Despite its pop culture bankability, the New York Times reports, the Today Sponge might generate comparatively little revenue: its failure rate can be over 10 per cent, and it doesn’t protect against sexually transmitted diseases.
OK, so it doesn’t really work, and it’s only available if you’re lucky. Other than that, it’s great!
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Véronique adds: I never watched Seinfeld but I distinctively remember the sex-ed class in grade 9 where the sponge was hailed as the best thing since slice bread. All I remember thinking was “Gross…” but then I went on to have 6 children so what do I know about contraception? Which leads me to wonder, when they write that the sponge’s failure rate can be over 10 percent, do they mean that out of 100 sexual encounters 10 will end up in pregnancy or that 10 will not protect you against pregnancy although you may not actually get pregnant depending on your cycle? Because if it’s the former, the failure rate is probably much higher than 10 percent. But then again, what do I know about how babies are made?
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Tanya says: Failure rates are a thing of beauty. They are often preceded by phrases such as ‘If used correctly’ or ‘it is estimated that.’ If used correctly, it is estimated that condoms have a less that 1 per cent failure rate. Which is good, right? And if you were flying at 2000 feet and the captain got on and said “Good morning! This is your captain speaking. It’s a balmy 30 degrees in Barbados right now and we should be arriving in a little over 2 hours. By the way, there’s a 99% chance this plane will get you there safely. Have a pleasant flight.” Well, see, I’m not sure that would go over too well.
by 
What the failure rate means is that out of 100 couples who use the sponge as birth control over the course of a year, over 10 will get pregnant.