Normal is however you define yourself, others, and your life on a regular basis. "To be normal, is to be weird. So in a sense if you're weird, you're normal." -me
Sure, some men erect just by seeing a hot girl, some men need to see them naked, but if you're looking at a naked woman and not erect then you may have a problem.
98.6F orally is the classic answer. Temperature varies throughout the day, lower in the morning and higher in the late afternoon. Temperatures over 100.4F are considered fevers.
Suppose you could call it the Gaussian Distribution or the Laplace-Gauss (not to be confused with the Laplace distribution which takes an absolute difference from the mean rather than a squared...