In this 5-page PDF, author Michael Hammes presents 12 spells "that feature unpleasant visuals, buckets of gore, stink like no one's business, etc.; in short, they are just plain sickening."
Warning: These spells can be particularly disgusting. Michael doesn't joke around when it comes to grossing out the players. DMs can have an especially fun time using these spells against the player characters.