Random tins can contain beans as their contents, which make you emit a stinking cloud when or after eating them.

Cursed boots that you have worn for at least 300 turns should emit a stinking cloud when finally removed.

Add an additional container trap effect which creates a stinking cloud centered on the container. If the player caused the cloud to be created, they are counted as responsible for anything killed by the cloud.

Breaking a wand of wind creates a stinking cloud centered on its space, because it’s “breaking wind”. Possibly only when cursed.