“Walao” and its variations are popularly used when someone is surprised, shocked in disbelief. This would be the Malaysian & Singaporean replacement of “Oh my gosh!”. Malaysians typically use it when there are mega sales, cheap
flight and hotel discounts on sale, whenever they get together at the mamak watching
football, and so on. It’s also typically used to compliment one’s skills, talents or achievements - or if your friend does something
stupid!
There are also other names you can use with "Walao", such as "Walao eh", "Walao wei", etc.
John (Driver): *Ignores traffic
light and just drive through because he's in a rush*
Jane (Passenger): Walao eh, next
time you will die if you keep driving
like that...