The Hard-headed Chimpanzees is a poetic riddle intended to describe a chosen subject, originating in The Hubristic Cohort. The rules of the form are applied by poets to produce individual poems which can be recited. The poem is a single couplet. Use of internal rhyme is characteristic of the form. Each line has six syllables. The ending of each line of the poem shares the same rhyme. The second line of the couplet is required to maintain the phrasing of the first line. The second line of the couplet reverses the grammatical structure of the first line. The second line of the couplet presents a different view of the subject of the first line. The first line concerns the past. The second line concerns current events.