to give some money when several people are giving money to pay for something together

They all chipped in £100 and bought their mother a trip to Greece. 他们每人凑了100英镑，让母亲到希腊旅游一趟。

to interrupt a conversation in order to say something

I'll start and you can all chip in with your comments. 我现在开始，你们随时都可以插话发表意见。