This paper presents a computer implementation that utilizes cross-reference ambiguity in utterances for simple conversational jokes. The approach is based on the SSTH. Using a simple script representation, it is shown that cross-reference ambiguities always satisfy the SSTH requirement for script overlap. To determine whether script opposition is present, we introduce a method that compares the concepts involved based on their semantic properties. When a given cross-reference ambiguity results in script opposition it is possible to generate a punchline based on this ambiguity. As a result of the low performance of the anaphora resolution algorithm and the data sparseness in ConceptNet the application performs moderately, but it does provide future prospects in generating conversational humour.