When the Uruk-hai bragged to the Mordor orcs that they were given man-flesh to eat, the Mordor orcs replied that it was really orc-flesh, and the Uruk-hai were

When the Uruk-hai bragged to the Mordor orcs that they were given man-flesh to eat, the Mordor orcs replied that it was really orc-flesh, and the Uruk-hai were offended. So, while it may have happened somewhere, at least both Mordor and Uruk-hai orcs considered the suggestion offensive.