Readers’ cultural expectations regarding literary masterpieces can hamper their experience of humor. This chapter studies the passage in Chrétien de Troyes’ Yvain in which the knight’s faithful lion is said to run like a frantic hog. This simile is so surprising that it has generally been ignored not only by medievalists but also by medieval translators of Chrétien’s Yvain. Yet its potential humor is highly significant, as its disruptive quality constitutes an astute response to the already disruptive thrust of Ovid’s legend of Pyramus and Thisbe. The comparative and intertextual approach of this chapter brings together, on the one hand, Chrétien’s romance with its translations in Middle English, Old Norse, and Old Swedish, and on the other hand, Ovid’s seminal legend with its medieval adaptations by Chaucer, Gower, Boccaccio, and the anonymous author of the Old French Piramus et Tisbé. In every work, the dynamics of perception and cognition are central to the plot.