I had noticed that more than one person was replying to my posts with pictures of women in bathing suits and it happened within the same few days (to which I would always reply with a vastly more disturbing picture), leading me to believe that they were concerted efforts and someone who I apparently offended was suggesting they do it.
They stopped, though, so maybe I'm just paranoid (I had a plentiful cache of horror yet to unload, too...).