I'm in Bangkok now and 5555 means hahahaha because the Thai sound for 5 is "Ha" and tonally, they say it with great joy. Thai people use 5555 (and more!) with great frequency on fb posts as do expats who are in the know.

When Thai people say the number 5 in English they also keep the joy in the tone. It's fantastic while you wait in line for your number at the bank or immigration. "Next Number - 6. 7. 5!!!!!!!" The six and seven and all the other numbers are a letdown in comparison to the 5.