When straight men suck each others balls to taste whether or not they can trust each other.
Men have special receptors on their tongues, similar in texture to a cats tongue, which can literally gauge another man's disposition by coarsely licking his balls.
I don't know if i can trust you, we'll have to perform an Oral-testicular psychocross-examination
When a wild, macho, "man's man" gets with a woman that dominates him and, figuratively speaking, castrates him.
Tony used to love to hang out and party all night, gettin all kinds of ho's! Then he got with this domineering b****, now he's suffering from testicular atrophy.