Similar hormones stimulate the production of sperm in men as those that women produce during pregnancy (might even be exactly the same, this stuff is rusty.) In any case, it is very possible for men to pee on regular old home pregnancy tests and get a positive.

The most hilarious thing about that post is the comments. People take this stuff entirely too seriously. Eventually there are commenters conducting actual statistical analyses about Star Trek characters As George Takei would say: "Oh my!"