دنیا دو روزه / donya do roozeh / the world is two days
After I said this phrase, I realized it's about the equivalent of you only live once or YOLO as is popular these days.
I don't know if I should blow my savings and take that trip I've always wanted to. Baba donya do roozeh!
Should I eat another piece of cake? Eat it! Donya do roozeh!
It's also used as a sort of consolation when someone is upset. You say donya do roozeh to convey the brevity of life and that you should enjoy it.
Here's the classic song of the same name by Aref. Hope you enjoy it!