abstract:The essay considers by editing, translating, and analysing two famous Irish jokes, first a celebrated exchange between the philosopher Iohannes Scottus Eriugena and the Emperor Charles the Bald, and second the Bamberg Cryptogram. From four sources, one poem by Theodulf of Orleans and three prose accounts by William of Malmesbury, Gerald de Barri, and Matthew Paris, the first joke can be understood to function in five distinct ways. The second part of this paper considers two works by Dubthach mac Máel-Tuile, a colophon and the Bamberg Cryptogram, a letter from Suadbar to Colgu explaining the code of the cryptogram, a colophon by Nandharius, scribe of the letter, a poem by a Welsh priest named Cyfeiliog using Dubthach’s code, and an account of scholarly needle in insular Latin literature. The Appendix by Colin Ireland discusses the Irish names in Suadbar’s letter.