Emoji symbols are being used to construct secret "languages" that allow personalised communication between colleagues, friends and family members, say researchers.
In the new lexicon, pictures of pizza or wedges of cheese popping up on a smartphone might mean "I love you".
Emoji symbols are being used to construct "secret languages" pic.twitter.com/tWGECc5k0i— RTÉ News (@rtenews) February 7, 2018
A bathtub symbol delivered a somewhat different message, according to one example cited by the scientists. It translated as "coffin".
An even more obscure meaning was attached to a "thinking face" emoji. Because of the position of the thumb and forefinger on the chin, it mirrored the American sign language symbol for "lesbian".
Other examples included an octopus emoji for "cuddles" and a devil image for "I'm feeling sexy".
Emojis used in combination took the place of whole sentences, the scientists found.
In once instance, a balloon followed by a comma and a teddy bear meant "I'm thinking of you but don't have the words to say it".
The team from Goldsmith's University of London and the University of Birmingham conducted an online survey to investigate how people used emoji to convey secret meanings.
Of the 134 participants, 74 reported "repurposing" 69 different emoji for private communication.
Dr Sarah Wiseman, a lecturer in computer science at Goldsmiths, said: "Our study shows that people use emoji in a similar way to nicknames or slang, as a handy shortcut to what they mean, which through consistent use creates an intimate 'secret language' others don't understand.
"Creators of emoji need to bear in mind the subtle way that people repurpose them and the impact even small visual changes to them could have on these alternative meanings."
In 2016, Apple faced a furious customer backlash after changing the appearance of its peach emoji.
An investigation found that most Apple users were using the emoji to refer to buttocks, with only 7% employing it to describe a fruit.
The re-drawn emoji did not fit the alternative meaning as well as the original.
Dr Wiseman added: "While we know some fruit and vegetable emoji have been repurposed by many people to mean something else, we were intrigued to find out about personal instances of this - examples of emoji that have a special meaning for just two people.
"Often this was about more than just typing something more quickly: people found that by using emoji they could convey very complex meanings and thoughts with them that could not be described in words."
The findings are due to be presented at the Computer Human Interaction 2018 conference in Montreal, Canada, in April.