Here's another interesting linguistic post from social bookmarking site Reddit - something that seems to be becoming a monthly ritual. This time in concerns internet slang, more specifically laughter.
Whilst acronyms like "LOL" and "ROFL" are pretty much almost universal now in the online world, the question posed was how people from different cultures denote the sound of laughter online. English's "hahaha" or "hehehe" sum up the sound of a hearty gut laugh quite nicely, but different languages have different phonetics for particular letters, leading to a variety of language-dependent 'shorthand' laughter.
Some languages are pretty straightforward - for example in Spanish laughter is often written "jajaja", since the letter J in Spanish has a similar sound (though they also use "hahaha").
The French have several nuanced versions, all of which have their own subtle meanings - "hahaha", "héhéhé", "hihihi" and "huhuhu". Their equivalent of "lol" is "mdr" - short for "mort de rire", meaning "dying of laughter".
However, some other languages are more creative. Thai, for example, use "555", since the word for the number 5 in Thai is "ha". In Korean they use ㅋㅋ (pronounced "kk" or "keke"), which sounds like more of a mischievous giggle.
In Japanese they use "wwww". "W" is short for "warau", the verb meaning "to laugh" in Japanese when transliterated into English (Romaji). They also use ふふふ (pronounced "huhuhu").
In Mandarin Chinese, they use characters with the same sound as laughing - 哈哈哈 ("hahaha") and 呵呵呵 ("hehehe").
For more examples from different languages, check out the original thread on Reddit.