Because pushing a parasite roughly the size of a clown's shoe that's been weighing you down for the past nine months through a bodily orifice that shouldn't normally stretch more than a couple inches wider than it's normal size is a lengthy, excruciatingly painful, and potentially life-threatening activity, and the average person likes to think that when they've shredded their genitals for someone else, they've earned some bragging rights, whether or not they decide to keep that person in their life?