It was four years ago and Charlie Burness was planning a fancy dinner for her mum's birthday.
But her mum didn't feel like a fancy dinner, she felt like KFC. They enjoyed the meal but when they got home the family was in agreement - KFC's chips let the team down.
Charlie, from London, sent this tweet.
I've got to say, KFC are riding solely on their chicken because Christ, those are crap fries.— Burnessie (@charliejburness) August 11, 2014
Now, the four-year-old dig at KFC has helped bring an updated chips recipe to the nation.
Last month, the fast-food chain got in touch with Charlie to ask if they could pay Twitter to promote her tweet.
It was planning to change the recipe of its chips and saw her tweet as a chance to reveal exactly why.
"I thought it was quite clever actually," Charlie tells Newsbeat.
"I knew it would grab attention because of the reputation their chips have."
So what's Charlie's main beef with KFC's chips?
"To be honest I think everyone knows KFC's chips are just not the best really," she says.
"Everyone knows they've got a reputation for not delivering on the fries. They're kind of soggy, like they've been reheated as soon as you get them."
Charlie says she takes "food and fries quite seriously" and "life is too short for bad food".
The 30-year-old hopes the new fries have a bit more crisp to them.
KFC says its new chips are made from spuds with the skin left on and will be chunkier.
Jack Hinchliffe, innovation director at KFC UK & Ireland said: "We don't change things on a whim - the Colonel's Original Recipe chicken hasn't changed since he finalised it in 1940.
"This was different though. We heard the nation's outcry. We read the brutal tweets. We had to step up our fries game."
It's not the first time the fast food chain has used bold marketing tactics.
In February, KFC apologised to its customers for running out of chicken in an advert in which its logo spelled out something pretty cheeky.