Doping

They concealed it about their person, and anecdotally a condom up the bum is best, then produced it when required in anti-doping.

It's been around for years and years. Michel Pollentier was ejected from the Tour in 1978 whilst wearing the yellow jersey for attempting to use someone else's urine, held in a condom under his armpit, when dope tested.

There's also an apocryphal story about a male cyclist being told after a urine test "great news: you're pregnant".

This method of cheating the control is exactly why testers are obliged to get samples from athletes in the nude, hence the move to catheterisation. A classic example of the cheaters finding a loop-hole in the testing regime, and exploiting it.