The idiom "get the third degree" means to be questioned or interrogated intensely or aggressively. It is often used when someone is being questioned by the police or other authorities, but it can also be used in other contexts.
For example, if someone is applying for a job and the interviewer asks a lot of difficult and probing questions, they might say that they feel like they're getting the third degree. Similarly, if someone is being questioned by their parents or a teacher about something they did wrong, they might feel like they're getting the third degree.
The origin of this idiom is unclear, but it may have come from the idea that there are three degrees of questioning: the first degree is a simple question, the second degree is a more difficult question, and the third degree is the most intense and aggressive questioning.
Overall, "get the third degree" is a useful idiom to describe a situation where someone is being questioned or interrogated in a very intense or aggressive way.
• I don't like going to the doctor because they always give me the third degree about my diet and exercise.
• My parents gave me the third degree when I came home late last night.
• The lawyer gave the witness the third degree during the cross-examination to get the truth out of them.
• The detective was known for giving suspects the third degree until they broke and confessed to the crime.
• The police officer gave the suspect the third degree during the interrogation.
• The journalist was giving the politician the third degree during the interview.