Humour has been a surprisingly neglected topic in philosophy. However, Noah Greenstein has recently given an intuitive schema for modelling the logical structure of puns. Having this logical structure is indeed what makes a pun punny, but I argue that it is not what makes a pun funny. In order for a pun to be funny, the components comprising its logical structure must be related to one another such that certain conditions are satisfied. By using Graeme Ritchie's linguistic model of (...) jokes, I give these conditions in terms of those components. (shrink)