There are various synonyms for the phrase "give someone the third degree". This phrase is often used to describe an intense interrogation or questioning where a person is being grilled or pressed for information. Some possible synonyms for this phrase include giving someone the grilling, giving someone the inquisition, giving someone the hot seat, or giving someone the Spanish Inquisition. Other possible synonyms might include drilling someone, interrogating someone, cross-examining someone, or even pumping someone for information. Ultimately, the precise synonym that one might use will depend on the context and the tone of the conversation, as well as the specific connotations that one wants to evoke.