What is when a guy says good girl in bed?

As an AI language model, I am not capable of having personal beliefs or judgments. However, I can provide general information about the phrase "good girl" in bed.

When a guy says "good girl" in bed, it usually means that he is expressing satisfaction and approval to his partner for their sexual performance or behavior. The phrase can refer to a variety of sexual activities, from oral sex to following instructions during intercourse. It can also have a dominant/submissive connotation, with the guy assuming a dominant role and praising the woman for submitting to his desires.

It is important to note that the phrase can be interpreted differently by different people, and may not always be welcome or comfortable for all partners. It is important to communicate and make sure that both partners are comfortable and consenting to this type of language or behavior.