Joke Decoder (panel 11)

Vert compliments his wife.

All the men can relate to this one.  How often have we legitimately offered a compliment to our wives or significant others — only to have them knock it down in disbelief?  Here Vert is complimenting his wife, Verta, on her beauty, as she tells him that he must be joking because her femurs [thigh bones] are much too calcified [calcium build up being analogous to fat].