fluster

★to make somebody nervous and/or confused, especially by giving them a lot to do or by making them hurry すごく焦る、うろたえる

●fluster somebody Don't fluster me or I'll never be ready.

●be flustered(by something) He was flustered by all attention. 

She was clearly flustered by Marshall's unexpected arrival.

get flustered

We get all flustered みんなうろたえる

The most flustered I have ever been was...