Jiàqī guò de zěnmeyàng? —— Biétíle, tiāntiān xiàyǔ.
How was your holiday? — Don't mention it, it rained every day.
Tips
usage
别提了 always signals frustration or disappointment. It's used to express that something went so badly that the speaker doesn't even want to talk about it. Sometimes followed by 多...了 for emphasis: 别提多难了 (don't even mention how hard it was).