Apparently, "monkey butt" is what can result when you spend hours upon hours on a saddle. The phrase comes from the world of motorcycling.
For bicyclists, the traditional way to deal with discomfort in the "taint" is by wearing bike shorts and applying various creams and salves. With the recent emphasis on wearing non-cycling clothing, I can see a demand for powders like this "Anti Monkey Butt Powder."
Anti Monkey Butt powder is talcum powder and calamine powder (zinc oxide). It has a very mild and non-offensive fragrance that's vaguely flowery, but it's not in the least overpowering to my sensitive nose. I just poof a little bit down my pants before I go bicycling and away I go.
You can buy Anti Monkey Butt Powder online or in some stores, especially stores that cater to bikers of the motorized variety. A "Ladies'" formulation is also available.