It is hot here damned hot. Try play Tennis in this heat - murder. Yet there are maniacs out on their bikes or running. Freaks, some people like to suffer. They say that 80% or something of heat is lost through the head. Sportsman will pay millions to gain any advantage real or perceived. I mean there were these fools paying a $100 for a small magnate around their wrists which "improved" balance and made you a bit like superman or not.
You need to make a cap (or perhaps a shirt - gloves) out of freezer gel inside a material. Surely a sportsman keeping cool would have an advantage and also be more comfortable. You put you special gel cap in the Freezer the night before, keep it in its custom made pouch and slip it on when the kitchen gets hot. All it would take is for it to be comfortable, effective and for one sports personality to wear it once and the next day you are a billionaire.
There are also medical application like migraine suffers and people undergoing chemo. Something exists for chemo so people do not lose their hair but it seems to be not very stylish and something you could not wear out the hospital.
I reckon the feasibility is pretty high. We need design and implementation