Season 7: Episode 119: The SpongeWhile sponsoring Kramer for an AIDS Walk, Jerry spots the name of an old college classmate on the sign-up sheet. Over Elaine's objections, he copies down Lena Small's phone number and calls her for a date. Worried that Lena would mind, Jerry then keeps secret just how he got the number until he's forced to tell George in confidence. But an argument over secrecy prompts George to tell Susan everything, including Jerry's secret. Meanwhile, when her favorite birth control device, the Today Sponge, is taken off the market, Elaine searches high and low until she finds the last remaining case.
When Susan sends him to pick up some birth control so they can make up after their fight, George discovers she uses the sponge, too. Knowing Elaine has the last remaining case, he heads for her apartment. But after refusing George's request to borrow one, Elaine also has second thoughts about sex with her boyfriend Billy for fear of depleting her precious supply. Meanwhile, Jerry's fears are confirmed when Susan starts a chain of phone calls which eventually lead to Lena hearing how he got her number. And Kramer's refusal to wear an AIDS Ribbon makes him a pariah among his fellow walkers.
Though George claims not to like them, Susan persuades him to use a condom for their "make-up sex. " But the pressure of opening the wrapper proves too daunting, leaving them unsatisfied. Then, after subjecting Billy to some rigorous questioning, Elaine decides to use one, but only one, of her sponges on him. Meanwhile, when Lena is okay with how he got her phone number, Jerry begins to think she may be too good for him. However, discovering her own large supply of sponges cause him to reconsider. But it's Jerry's other little secret -- changing the size on the label of his jeans to make them appear smaller -- that finally turns Lena off.