Forget flowers this Valentine's day, the new way to say 'I love you' is with a penguin or pizza emoji.
The popular digital symbols are being used in personal "secret" languages as revealed in a new study.
"Special meanings" were uncovered by researchers at Goldsmiths University in London, who uncovered a mixture of affectionate and sinister symbolism in the icons.
Dr Sarah Wiseman, co-author of the study 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."
The research paper, ' Why [pizza emoji] means "I love you"' found that in secret emoji-languages, pizza and cheese stood for signs of affection after a mutual love of the food between recipients.
The researchers will present their emoji paper at the Computer Human Interaction conference in Montreal, Canada this April, which includes why a bathtub emoji represents death and how six per cent of texters use emojis to symbolise criminal activity and sex.
In an online survey, the team investigated how individuals personalise emoji to create unrelated meanings and found that nearly half of the meanings were between lovers, who most commonly referred to each other through penguins.
These alternative meanings can be assigned randomly but can become permanent and are used consistently over time between partners, friends, or family members.
Sexual-orientation symbolism also featured among the participants, with one user writing the 'thinking face' to mean lesbian, as denoted in American Sign Language through the position of the thumb and forefinger on the chin.
Co-author Dr Sandy Gould said: "Normally used for speed, some emoji are instead used to convey intimate and personal sentiments that, for many reasons, their users cannot express in words."
The study of 134 people found that 28 percent of users rejected conventional language and used emoji as a form of written convenience.
The experience of using emoji can also promote intimacy according to Dr Gould, by helping people feel closer to one another through a shared meaning.
In 2016 there was a furious customer backlash against Apple for changing its peach emoji to look less like buttocks, as Apple research showed just seven percent of users referring to the foodstuff with the juicy icon.
Dr Wiseman said that the creators of emoji must bear in mind the subtle way that people repurpose the icons and consider the impact their design could have on alternative meanings in the future.