Should I Sign Performance Improvement Plan?

The short answer to that question is yes, you should sign your PIP. To make sure that management cannot use these characterizations against you later, write below your signature something like “I sign only to acknowledge receipt of this document.”

Does a performance improvement plan mean I'm getting fired?

You therefore need to take it seriously and commit yourself to the goals of the plan. While it does not mean that you will get fired, some companies take it as a warning to their employees. ... You should really take some time going through the plan to ensure that you fully understand what is needed of you.

How do you fight a performance improvement plan?