A woman has left social media users in shock after discovering a secret 'code' inside a Costa cup.

Tinesha Kinley, 22, a barista from Leeds, was holding her friend's coffee when she noticed that the 'o' in the logo had been coloured in on the lid.

The 22-year-old soon realised this had been done to distinguish that the drink had been made from oat milk, but then something else clicked.

In complete shock, Tinesha figured out that all the letters in Costa's name stand for the different kinds of milk the chain uses in their drinks.

The amazed barista shared her discovery online, wracking up more than 687,000 views and 34,600 likes.

"I was in the car with my best friends driving home from London to Leeds and we got my friend who was drinking a coffee from Costa," Tinesha told NeedToKnow.Online.

"She ordered an oat latte and as I was holding it in the car for her, I noticed how clever it was that instead of writing “oat” on the drink, they coloured in the 'O' of Costa instead.

"I brought this up to my friend and that was when I realised that the letters were codes for the different kinds of milk.

"I thought it was so cool, especially since I’m a barista myself.

"It would be so quick and easy to colour in one of the letters so you know what milk has been used instead of trying to awkwardly write on the side of the cup.

"'C' for coconut milk, 'O' for oat milk, 'S' for soya milk, 'T' for traditional milk and 'A' is for almond milk."

In the clip posted online, viewers can see Tinesha holding the cup with the 'O' coloured in.

In the video, she writes: "Costa has the perfect system for our plant-based milk a**es.

"Their name has the first letter of every milk option HOW CONVENIENT IS THAT." [sic]

The discovery has left many users stunned, including people who claim to work at the coffee chain.

One person wrote: "I’ve been working here for over a year, how have I not been doing this."

"ITS MY FAVOURITE THING WHEN THEY COLOUR IN THE LIL ‘S’ FOR MY SOYA COFFEE!," said someone else. [sic]

Another person wrote: "They did this and when I drank I got sharpie stain on the tip of my nose and didn’t notice it until I joined a teams call."

"Tell me why I worked at costa and only ever noticed this and did it for coconut milk oml i'm acc so blind," another person said. [sic]

Someone else commented: "no I work there I love it, c can double up as caramel and chai, s can be skinny." [sic]

ENDS

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