PETA has engaged in a variety of ads that are often deemed controversial, to say the least. Either because of their comparisons to atrocities that occurred to human animals, or for their racy and/or sexist content. The later reason being why a PETA ad was nixed from the superbowl.
However, PETA has created a commercial to run during the Macey's Thanksgiving Parade, and it was refused for no clear reason by NBC. Watch the commercial yourselves, and realize this is a completely absurd decision.