If you're a top athlete at a massive competition, the last thing you want is to be sprinting to the loo to be sick!
But that's what's happened to some of the British swimming team at the Commonwealth Games in India.
A fifth of the team have a tummy bug, including Fran Halsall, who had to run off and be sick minutes after winning a bronze medal on Wednesday.
Games bosses are now trying to find out if there could be a problem with the pool that is making the swimmers sick.
Fran had to cut short an interview after winning bronze in the 100m freestyle because she was feeling ill.
Fran celebrates with her medal - despite feeling sick!
She told a BBC reporter: "I don't think I'm very well to be honest. I came down with a bit of a tummy bug. I pretty much couldn't stand up after my final. I need to go before I am sick on you."
Commonwealth Games Federation chief Mike Fennell said he was taking the problem very seriously.
"We must find this out immediately," he said. "If there's something unsafe you can't swim in that water."