Punning is a form of humorous wordplay based on semantic ambiguity between two phonologically similar words - the pun and the target - in a context where both meanings are more or less acceptable. While the pun is expressed explicitly, the target is invoked implicitly in the text. Previous work has attempted to quantify and compare phonological features of puns and their targets, looking at correlations with the understandability of the jokes in which they occur. Our study quantifies the phonological distance between pun and target words and assesses possible correlations with funniness ratings of the corresponding jokes. Our statistical analyses on a large dataset of puns reveal a significant negative correlation between phonological distance and perceived funniness for two of the four phonological distance measures we applied. This finding supports the hypothesis, often (implicitly) made in previous research but never verified at this scale, that lower phonological distance between a pun and its target is associated with higher funniness ratings. The parameters of our study suggest that future work should examine the semantic features of pun and target in order to create a more holistic understanding of what contributes to the perceived funniness of punning jokes.