Freddie Flintoff had to see a doctor after his member went numb and was "like a dead fish" during a charity bike ride.
The 'Top Gear' host admitted he "suddenly" lost all feeling in his "old fella" three days into a marathon trip from Athens to London.
He said: "It just suddenly went numb, as if I’d trapped it in a door. It was like a dead fish.
“I said to the medic, ‘Doc, I’m afraid you’re going to have to have a look at my old fella, I can’t feel it’.
“He took a look and was quite blasé, ‘Oh, that’s quite common in cyclists.’
"I was quite taken aback. Apparently, it was to do with something called the penile nerve.
“The old fella only started to resurrect itself about three days after I arrived in London.”
Former cricketer Freddie joined retired rugby star Lawrence Dallaglio on the 2,872 mile Cycle Slam ride back in 2012, which took them 26 days and saw them raise £2 million for charity
The 42-year-old star also finds it embarrassing wearing Lycra to cycle because the tight material "doesn't leave a lot to the imagination".
According to The Sun newspaper, he wrote in his book 'Right, Said Fred': "I feel like I'm exposing myself. Nobody needs to see that."
Freddie recently opened up about his battle with bulimia, and admitted that while he wanted to ask for help in his 20s, he felt he didn't have the "right" to have an eating disorder.
The star - who recently fronted documentary series 'Freddie Flintoff: Living With Bulimia' - said: "We had a dietician come in to speak to the team. I was at that point where I was about to say I have a problem here.
"She signed off by saying that she worked with a lot of women... and she wouldn't imagine there was anyone with an eating disorder in the room, because we were a group of lads, obviously.
"I didn't feel like I could speak or say anything. Being a bloke, 6ft 4 and from Preston, I'm not meant to have an eating disorder by rights. So, you keep it hidden away and you don't want to speak about it."