[1] whatever; wishy-washy; anything goes; as one pleases; not confirming to rules; casually; randomly | [國] 隨便
[2] a common term for 豉油煎蛋飯 (due to its being nearly homophonous to 豉蛋), which many kids love to eat in HK, and often used as a joke for people who reply to "what do you want to eat" with "是但", the comeback being "豉油煎蛋飯呀?" (could mean "are you still a kid?" or "are you that cheap?" because it's just soy sauce and a fried egg on rice).