To the phrase "we must not prove anything to anyone" I will immediately answer - you too are not obliged to not consider lazy fat pigs.
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How is a courteous man different from a ham?
A courteous man keeps his valuable opinion with him. Ham expresses his opinion aggressively, calling other people "ghirobas" or "lazy fat pigs." Or with a "soup set", "grey mouse", "smalled", "cock", "drisc" - well, depending on preferences.