These things can usually be traced to single sources, like a magazine article or radio host, which is then repeated by other media sources scrounging for content, who are just repeating what others have said, absolving them of journalistic responsibility, apparently. With multiple seeds planted, these ideas start to root in pop culture and word of mouth.
I don’t remember the Richard Gere one specifically, but the term “felching” was all over the place for a while, some shock jocks had a classic description of an anal mortar incident which was an early viral email attachment, until Lemmiwinks took the whole idea to a new level and dismantled it in absurdity.