(Serious): Male genital protection for mountain biking/BMX and for common falls I want to start using a protection like a helmet for is for the head, but for my penis and testicles. 

Why is important? It would give me much more confidence when triying new tricks and tecniques to not fear my genitals will be hurt, simply falling  in the wrong way could hurt me very bad.

I shouldn't worry? Well I do and maybe others don't, however I'm not neither the best biker that never falls, neither I think nobody should put others to that standard. If others don't want it ok, I need it.
Genital protection is rarely (if ever) used in cycling because it generally means putting some kind of hard surface in play (or excessive padding).  Either of these can easily lead to some very uncomfortable chaffing problems.  For less "pedalcentric" disciplines this might be acceptable (flatland, downhill, etc).  But, for the rest of the market there just isn't a benefit to loss ratio to justify it.

Many other sports have genital protection equipment that is used regularly.  Like winter cyclists who have to use mountaineering equipment to stay warm, you may have to dip into some other sports equipment cache to accomplish / try what you are suggesting.