tip (v. & n.)
给(小费)

例句：
I tipped the waitress 30% because she was so friendly.
我给了这位女服务生三成的小费，因为她很友善。

I gave the waiter a fat tip.
我给了那个服务员很优厚的小费。

burn one's fingers
自寻烦恼、自找苦吃

例句：
It was too late for him to regret as he had burned his fingers.
他因管闲事而自找苦吃，真是后悔莫及。


Help yourself, please.
请随便一些。

对话：
A: I like this chicken broth. Can I take some more?
B: Why, of course. Help yourself, please. There is plenty left.

A：我喜欢这鸡汤。我可以再喝一点吗？
B：噢，当然可以了。尽管喝吧。还有很多呢！