What are /r/BadMensAnatomy's favorite Products & Services?

From 3.5 billion Reddit comments

I didn't search extensively, but there are studies showing that smoking marijuana lowers male fertility, but that's more "lay off the weed if you're trying to get pregnant" than "weed is an effective birth control method."

There is underwear that works like that, although you're unlikely to encounter it outside of gay clubs with go-go dancers.

You're close but the facts are off a bit. For a quick read, here's his Wiki page David Reimer. For an in depth read, there's a book about him "As Nature Made Him". It not only tells his story, but delves into the "nature vs nurture" bit.

Males have penises, females have vaginas, just like a male or female plug. This is what physical sex is, and it's not something that's up to interpretation. If you have a penis, you're a male.

"Man" and "Woman" refers to gender identity, which is separate from sex. It has to do with how a person sees themselves, and is entirely up to their own experience and identity. It's not something that can be "proven" any more than someone's favorite color. If they say it's true, it is.

Cis- and Trans-men are all men, but cis-men are male, and trans-men are female.