The idea for the Shower Toga stemmed from Peterson and her family's participation in obstacle races and mud runs. After the competitions, they were always left dirty and muddy, with no privacy to shower off and change into clean clothes. Peterson told the Sharks Shower Toga can also be used by people like surfers, hikers and music festival attendees.
O'Leary wasn't convinced: "Isn't your competition a garbage bag?" O'Leary asked.
No, Peterson said. "That's like saying a balloon is the same thing as a condom." She argued that a garbage bag, has slits on the side and gaps, making it much less private. Judge Lori Greiner added that a garbage bag leaks.
"I love your energy," O'Leary said to Peterson. "You are really aggressive. It's fantastic. But I don't like to invest in products where the competition is a garbage bag that costs 99 cents."
The other judges were intrigued, however. Shower Toga had good margins, had done $80,000 in sales and had attracted interest from a range of people, including caretakers for the elderly and race car drivers. When asked by guest judge Webb what the business means to her personally, Peterson got emotional.
"Five years ago, I got breast cancer, and I just needed something to bury myself into, " Peterson said. Peterson also mentions she wants to use Shower Toga for disaster relief, helping those affected get clean and safe.
Cuban and Webb are sold — although they note the name of the product needs to change to convey more clearly what it actually is, they said. Peterson was seeking $80,000 for a 33 percent stake in her company, but Cuban and Webb offered a joint deal of $80,000 for 40 percent. Peterson accepted.
Despite the deal, O'Leary remained doubtful. "Now that she's gone," he said, "you've bought a garbage bag with a string on it."
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Disclosure: CNBC owns the exclusive off-network cable rights to "Shark Tank."