Farrah Abraham -- Sex Tape Bikini YANKED Off Ebay

The sale of the bikini Farrah Abraham wore for the cover of her sex tape has hit a snag ... eBay has pulled the listing down because it hasn't been washed since she wore it.

As TMZ first reported, Vivid Entertainment -- the porn studio behind the release of "Farrah Superstar: Backdoor Teen Mom" -- listed Farrah's pink crystal-encrusted two-piece with a starting bid of $500.

We're told eBay removed the listing and sent Vivid an email, saying, "Due to health and hygiene concerns our policy does not allow used clothing to be listed on the site unless the item has been washed first."

When the listing was pulled, bidding had reached a whopping $14,700!!!!!

We're told Vivid will wash the bikini and re-post the listing in a couple of days.