(Twitter/McDonalds)

A Twitter campaign by McDonald's that aimed to allow users to share their favorite memories of the burger chain backfired when hijackers took over the chain's hashtag to tell horror stories of bad food and service.

The fast food giant launched a 24-hour promotion last week using the hashtags #MeetTheFarmers and #McDStories as part of a month-long "Supplier Stories" campaign. But when Twitter users began posting unsavory #McDStories, McDonald's knew it had a problem on its hands.

"McDStories…a nice juicy Filet o'fish. With added worm. Still alive. Nice. Never again," wrote Twitter user @flatfootphil, and "Found a dirty band aid in the bottom of take out bag..McDStories," wrote @HarrisonSJ.

McDonald's said today that the company had to switch course in the middle of the promotion, pulling the #McDStories hashtag and going back to the earlier, less inflammatory one.

"While #meetthefarmers was used for the majority of the day and successful in raising awareness of the Supplier Stories campaign, #mcdstories did not go as planned. We quickly pulled #mcdstories and it was promoted for less than two hours," said Rick Wion, social media director for McDonald's, noting that the #McDStories tweets made up just 2 percent of messages about McDonalds that day on Twitter.

The tweets ran the gamut from serious critiques of McDonalds' nutrition and food quality to funny anecdotes of peoples' experiences at the drive-in late at night.

One of the worst, by Twitter user @MuzzaFuzza, slammed the restaurant, saying "I haven't been to McDonalds in years, because I'd rather eat my own diarrhea."

Others played off the McDonald's hashtag, joking "McDStories: McDialysis? I'm loving it!"

McDonald's switched back to the original hashtag, #MeetTheFarmers, and the #McDStories Tweets eventually died down, Wion said today.

It was the latest in a string of corporate marketing campaigns that have gone awry when social media users put their own spin on ideas.

In February, Kenneth Cole faced backlash after using the uprising in Egypt to try to market its products, tweeting, "Millions in uproar in #Cairo. Rumor is they heard our new spring collection is now available."

Australia's Qantas Airlines, as part of their "Qantas Luxury" campaign, invited Twitter users to describe their "dream luxury in-flight experience" for a contest, provoking angry responses from customers. One user said their answer was "more than 3mins notice that the whole airline is on strike," while another use said their answer was to "choose Singapore Air luxury instead."