In Singlish (a creole language spoken in Singapore, made up mostly of English, Malay, and various Chinese languages and dialects, but taking a bit from every language spoken in Singapore), the word "lah" is used at the end of a sentence for some of the following meanings: * Make a command less rude-sounding ("Go away!" vs "Go away lah!" - the second is more polite, maybe even a little playful) * To indicate impatience or anger ("I dun know." vs "I dun know lah!" - the second indicates frustration with the situation, like "stop asking me already!") * To try and make someone feel better about something they're upset about. * Almost anything else, depending on the tone of voice you say it in and the context of the rest of the conversation. The word most probably comes from Malay originally, but in Singlish "lah" is far more versatile and has way more uses than in Malay.