The Chamber of Secrets 

A female restroom.

Bill, Jim, Tod, and Alyx waited, hiding behind a corner as brave Chad stealthily made in his way into the Chamber of Secrets to see what exactly made it such a welcoming place to share gossip, stories, rumors, and the like between the female species. When he got in there all he found was 4 stalls, 2 mirrors, 2 sinks, and a garbage can and was greatly flabbergasted as to how this place could be like an overcrowded grocery store given the right moment of time during the day.

The Chamber of Secrets by Knowledge Pool April 22, 2013

The Chamber of Secrets 

The act of dumping 100 proof or higher alcohol into one's anus, which is put in position above one's head (doing a headstand is the most accepted way to do this) and then lighting the alcohol on fire.

Ron Weasley did the Chamber of Secrets and now the whole room smells like burnt red ass hair.

The Chamber of Secrets by Dunhloke July 25, 2011