请随便。

You can use it as a standalone sentence. If a friend enters your house, just say 请随便. You can also add it to the end of an invitation. For example, 'The snacks are on the table, 请随便.' It functions like a verbal shrug that says 'I don't mind what you do.' Use it to break the ice when someone looks hesitant. It instantly lowers the social tension in the room.

Use it when hosting people at your apartment. It is perfect for buffet-style dinners where people serve themselves. In an office, use it when a client arrives early. You can even use it when someone asks if they can smoke or take a call. It shows you are an easy-going person. It is the verbal equivalent of a comfortable sofa.

Do not use it if you actually care about the outcome. If you have a specific seat for someone, don't say 请随便. Avoid using it with very high-ranking officials unless you are the host. Sometimes, it can sound a bit dismissive if said too quickly. If your tone is cold, it might mean 'do whatever, I don't care.' Use a warm smile to keep it friendly. Don't use it if the choice is actually a big deal.

Chinese culture often involves complex etiquette and 'mianzi' (face). Guests often feel they must wait for the host's signal. 请随便 is the host's way of releasing the guest from these rigid rules. It signals a shift from formal 'guest' mode to 'family' mode. Interestingly, 随便 on its own can be a bit lazy or indecisive. But adding 请 makes it a polite command of freedom. It reflects the value of making others feel unburdened.

You will often hear 请随便坐 (Please sit anywhere). Another common one is 请随便吃 (Please eat whatever you like). If you want to be extra polite, say 请大家随便一点 (Please everyone, be a bit more casual). In very informal settings with close friends, you can drop the 请 and just say 随便啦. This sounds much more relaxed and 'chill.'