Take the Fifth
Definition - What does Take the Fifth mean?
Taking the Fifth refers to a situation where a person chooses to not speak at a testimony due to the risk of self-incrimination.
The Fifth Amendment forbids forcing witnesses to provide testimonies that incriminate themselves. This is why it is called taking the "Fifth." It is also known as "pleading the Fifth."
Justipedia explains Take the Fifth
Taking the Fifth is an option that many people choose to use if there is a chance that they could bring about their own arrest and prosecution while giving a testimony.
For example, if a witness knows that they are an accessory to the crime, and that providing a testimony would reveal this information, they may plead the Fifth to avoid self-incrimination. However, this will not stop law enforcement from investigating the issue further.