This picture of copulating dogs is the only depiction of sex in a tomb occupied by two men who are shown in an eternal embrance in their burial chamber (see www.egyptology.com).
 

This picture is structurally very similar to the following picture from Old Babylonia (approximately the same era), depicting a man with a (non-)male temple prostitute, an "assinnu." (see Born Eunuchs: Homosexual Identity in the Ancient World, Section 3: Eunuchs Sexually Active with Men, note 74.)