Suit Yourself!
Do whatever you want to do / Relax
Suit yourself! I will come in 10 minutes.

Cross your fingers
Let us hope it happens/ Let us hope for good luck
The meeting is over, let us work hard and keep our fingers crossed.

Show them who is the boss
To clear somebody that you have more power/ to show who is more powerful
Let us show our competitor who is the boss

It’s up and running
It is working fine/ perfectly/ working properly
Our server issue is resolved now, it’s up and running.

Go Dutch
Pay for himself/ herself
I don’t want you to pay for my coffee. Let’s go dutch.