The best part about fast food is the speedy service.

Depending on how busy the location is, you don't have to wait too long until a tray of cheap food is handed to you.

The downside to this fast-paced environment is that staff members may not have enough time to adhere to food safety.

In the past year, customers claimed to have found a cockroach in their burger, rat feces in a bag of buns, cleaning solution in coffee, and bleach in burritos.

All these stories have gone viral, and for good reasons. We know that fast food isn't the healthiest option, but we don't expect it to stray from the ingredients you can find on their website.

"For those of you who can't tell, these are MAGGOTS."

One fast food customer recently took to Twitter to complain about her recent experience at a McDonald's location.

She claims that she saw live maggots in a ketchup dispenser, and even has video evidence to prove it.

"Never going near the ketchup at McDonald's again," she wrote. "For those of you who can't tell, these are MAGGOTS."

Isabella's stomach-churning video was filmed at a McDonald's in Cambridge, England.

"I told one member of staff and she literally just ignored me and carried on serving customers," she wrote.

Isabella added that she spoke to the manager and even emailed them.

"We had to literally stop someone from eating it because they didn't realize."

People who watched the viral video were equally as horrified.

"Oh my god disgusting!" someone wrote.

"You could actually sue, especially [because] they're still serving food," another commented.

McDonald's UK caught wind of the video a day after it was posted, and said they'll conduct an investigation:

"I'm very sorry to see this happened. So we can investigate, can you please send us a DM and let me know which restaurant this was and the time of your visit? Our teams will then be able to look into this for you immediately."

Do you see maggots in Isabella's video below?

A spokesman for McDonald's told the Sun Online: "We're extremely sorry to see this, and have tried to get in contact with the customer directly. Our condiment area and dispensers should be checked for cleanliness every day and we are looking into what happened here."

This isn't the first time someone claims to have found maggots at McDonalds.

Last year, an Australian woman allegedly found maggots in her McDonald's double Quarter Pounder.

She posted footage of her meal to Facebook, zooming in on the box, where you can see small insects moving around.  

"They're in the meat patty," she added, zooming in on the cheeseburger that was bitten into.

"How dare they serve this to unsuspecting customers. Michael unfortunately finished his before I seen it and is violently vomiting," she updated her followers.

McDonald's Australia denied the woman's claims.

"It's not possible for this to occur in our restaurants. Our food is cooked at incredibly high temperatures," a spokesperson said, according to Daily Mail.

[H/T: The Sun]

Have you ever encountered something strange in your fast food meal?