The fundamental particle responsible for manliness, the testeclon caries with it all properties typically associated with being manly. The only known source of testeclons is testicles.
The testeclon is a massless particle, and thus can travel an infinite distance, which it does at the speed of testacularity. The speed of testacularity is constant in a vacuum, equal to T=Ac^2, where c is the speed of light, and A is Bamfington's first coefficient, 100 seconds/meter. However, unlike the speed of light, which only decreases when it light propagates through a medium other than vacuum, the speed of testacularity can actually increase when propagating through some mediums, for example, women, or giant killer robots.
The fundamental equation governing the propagation of testeclons is: (lambda)(nu)=Ac^2, where lambda is the wavelength and nu is the frequency of the testeclon in question. The energy and momentum of a testeclon are equal to the same value, unlike other particles, and can be determined by the equation p=E= B (nu), where B is Bamfington's second coefficient, equal to the biggest number you can think of plus one. Testeclons are non-Heisenbergian particles, meaning that they are not subject to the uncertainty principle. This is because testeclons are always certain of what they are doing, and thus don't have to screw around with maybes or probability functions.

It is possible to determine how manly someone is by analyzing the intensity of testeclon radiation emitted.

When you eat dirt for the first time and leave your family to build a shack in the woods