To start off this was a long running 3.5 campaign which the DM liked to build our quests and such based off of songs.
This particular quest was based off Phantom of the Opera, in which our party chose to watch or compete in a talent show.
During the show a competitor (a very attractive young woman of posistion) gave a very moving performance, singing a haunting melody. After which, she was kidnapped by a mysterious masked man (the Phantom), and our party was charged with saving her.
We eventually tracked his base down deep within the city sewers fighting some constructs along the way, and came to the Phantom's room, trudging through over two feet deep water that was less than sanitary the whole way (worse for me as I was a gnome).
The battles for the woman began and we discovered the Phantom was a caster. One of the first spells cast was Hideous Laughter on our druid.
The druid rolled low, failing her save, and the DM decreed she fell to the ground and could do nothing but roll and laugh uncontrollably.
The party looks at each other with concern and ask "aren't we in like 2 1/2 feet of sewer water?" The DMs face mirrored our concern, and confirmed this. The druid was now drowning, unable to hold her breath beneath sewage, breathing in the tainted water.
We managed to survive the encounter, but we and the DM learned even the lowest level spells can prove both deadly and disgusting in the right situation.