I DUNNO, THEY MAY KEEP YOUR GUYS COOL BUT THEY DON’T HEAT UP THE LADIES: A Kilt Is A Sperm’s Best Friend. Still there may be something to it. When I was single and had a hot tub in my bachelor pad, I always hoped it was reducing my fertility. Recently a friend of mine impregnated his wife after several years of trying, only after taking several months off from the hot tub.