Myth-Nomers and Im-Pervections — Robert Asprin

How could such a thickheaded demon be so thin-skinned? But Aahz, Skeeve's friend and mentor, has taken exception to something his partner has said, and left in a huff. It was just a myth-understanding, but now it's Skeeve's job to apologize for his thoughtless behavior and convince his scaly cohort to rejoin the firm. So Skeeve finds himself in the missing Pervect's home dimension, the worst neighborhood in the multiverse, where jokes are a felony . . . and courtesy a myth-demeanor!