If I had a dollar for every time, during a same sex marriage argument, someone against same sex marriage brings up polygamy, incest, or pedophilia, I would be very wealthy.
(For the record, I actually do think polyamory, if done ethically (including, for instance, everyone involved consenting), should be legal.)
Also, if I had a dollar for every time somebody used "it's" when "its" was meant (or vice versa), I would also be incredibly wealthy. (In another topic, I saw two consecutive posts in which that mistake was made.)