Ludicrous means absurd, ridiculous, or unreasonable. In sentence number two, it says "He cracked jokes that were ludicrous." I know this is the meaning because the sentence suggests that Tanner's jokes were absurd or ridiculous, causing the class to laugh. This implies that his jokes were unreasonable and not appropriate for the serious topic he was supposed to present on. Ludicrous means absurd or ridiculous because in the passage it says that Tanner's jokes were ludicrous, causing the class to laugh but frustrating the teacher.
Actually, the sentence "He cracked jokes that were ludicrous" does not suggest that Tanner's jokes were absurd or ridiculous. It simply means that Tanner made jokes during his presentation. The word "ludicrous" in this context is used to describe the quality of the jokes, not their level of absurdity or unreasonableness. It implies that the jokes were funny or entertaining, but it does not specifically convey that they were unreasonable or inappropriate for the topic.
