5555 = lol = ha ha ha ha ha. (the number 5 is pronounced ha in thai)
Exactly the opposite in China. If a person played in the stock market and lost 80% of his money in less than a year, he'd add "55555555" to his description. Which means the sound of crying, pronounced as [wu:]. This phenomenan is rather common in some sites about stock markets in China, after they have just dropped from the record high of 6000 to 1600 points or so.
I just read 5 is pronounced as ha in thai, so 5555 should be hahahaha then.