'L'expression "cousinage à plaisanterie" ou simplement "cousinage" est largement utilisée au Sénégal pour décrire un ensemble de pratiques de plaisanterie et de relations privilégiées entre individus par le biais de leurs patronymes ou de leur communauté d'appartenance'. From an article about Senegalese tribes people.
I know this is an old thread, but popping in just in case others will find this helpful in the future.
Cousinage in the West African context is most commonly written as "joking relationship" in English. ("Joking kinship" would also be understood, but it's not precisely correct--people are not pretending to be relations or 'cousins' as the French word might imply. "Fictive kinship" in which people call non-relations by family terms is also used in West Africa, but is distinct from joking relationships).
Joking relationships are not between people of the same family name, as suggested above, but rather between members of different families, status groups, or ethnic groups. Because of historical events or pacts between their ancestors, if for example a blacksmith meets a cattle herder (identifiable by their last names which indicate their ethnicity and traditional occupations) they are allowed to mercilessly make fun of each other and insult each other. Some would even say they are obligated to do so! Joking relationships are credited with making the societies in which they are practiced more peaceful, because in addition to easing tensions through humor, people in joking relationships also have obligations of mutual support to each other.
Joking relationships are called kal in Senegambia and senankunya (with a variety of spellings) in several Mande languages.