Orginated from hokkien langguage widely use in SINGAPORE. Now the words have spread to their neighbour country MALAYSIA.
Wa-Lau means "Oh my DAD", same meaning of some people say "Oh My GOD". Because the founder was not a religion guy, so instead of using the GOD, it use his own DAD.
Some might use WA-MA! mean "oh my MOM" for those mummy's boy.
And last but not list, the "eh" is just a finishing touch to enchance the words Walau or Wama!
Walaun is used by the opposition party supporters (mostly by hardcore supporters) of Parti Se-Islam Malaysia to refer to their hardcore supporters. Some hate it, and some don't care but another version of "walaun", "malaun" which is a pejorative term for Bengali Hindus has been claimed "more ruder" by a PAS supporter. The opposite of "walaun" is "macai". This word was made popular during the 2022 Malaysian general election.