Viewers saw the Olympic swimmer telling the other celebrities in her camp on Monday night (18 November) that "everyone" does it because you can't just leave the pool when you're in the middle of a training session or race.
Well, we can understand that. Her fellow campers, however, appeared a bit stunned by her revelation.
"I always pee in the pool," said Rebecca. "Everyone pees in the pool. You can't just get out in a swim session. Everyone that swims does it. If you have the opportunity to get out and go, you get out and go, but if you can't get out, you just have to go."
EastEnders actress Laila Morse joked: "Lucky you don't want a dump then!"
Very true… and what an image.
Joey Essex quizzed Rebecca on whether pool water really turns purple when it comes into contact with urine but Rebecca assured him that wasn't the case.
I'm A Celebrity continues Wednesday on ITV.
Check out the full I'm A Celebrity 2013 lineup in pictures: