When Vince Offer was trying to sell you a Shamwow and said Olympic divers use them, he wasn't just being a blowhard. He was being a blowhard who had his facts straight, more or less. You might have noticed that Olympic divers in Rio aren't using a nice soft towel, but a tiny towel they are fine leaving over their shoulder while they shower.
They're actually using shammys, like a dad who is a little too concerned about water spots on his new car. Those rayon or poly-vinyl towels are capable of holding 10 times their weight in water and dry out almost instantly after they're rung out.
And that's what it's all about for divers: Finding a way to get completely dry between dives.
In a dive, the athlete is often gripping their legs or other body parts. If their legs are wet it can be difficult to get a good grip, raising the possibility that their hands will slip. Slipping can mean losing control mid-dive and it can mean lost points.
Using a shammy helps the diver to get their hands and legs almost completely dry, leaving them just moist enough to get a good grip. It's a routine done by all divers. It became standard practice in the '60s and '70s when some Norwegian and European divers began to use them.
Now divers can get completely dry and focus on the important things, like having an awesome, suggestive name or trying to avoid marriage proposals during medal ceremonies.