Every year around 1 billion Valentine cards are sent. After Christmas it's a single largest seasonal card-sending occasion.
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In Korea, if you do not receive any gift on Valentine's day then all the singles go to Korean restaurants and eat black noodles to celebrate (or mourn) their single status.
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When you fall in love, that 'high' feeling is caused by a flood of dopamine that is similar to that of cocaine.
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In medieval Italy, if a man was caught kissing a woman in public, he had to marry her whether he liked it or not.
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When a male gentoo penguin "falls in love" with a female penguin, he searches the entire beach to find the perfect pebble to present to her.
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Falling in love raises levels of nerve growth in a person's brain for about a year and can improve their memory.
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Sandy, an African Penguin, has been in 'love' with her keeper at the Nuremburg zoo since 1996.
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