Wiktionary
prov. (context idiomatic English) (non-gloss definition: Used as a mockery to someone who is about to be or should be confined in prison).
Wikipedia
Don't Drop the Soap is a controversial prison-themed board game designed by art student John Sebelius as a 2006 class project at the Rhode Island School of Design. The game received criticism for its content, most notably for the game's treatment of prison rape. Sebelius also received notice for being the son of Secretary of Health and Human Services Kathleen Sebelius and U.S. Magistrate Judge K. Gary Sebelius. The game officially went on sale on January 31, 2008 in Lawrence, Kansas and through Sebelius' personal website, and is considered to be similar to Monopoly in its gameplay.
Usage examples of "don't drop the soap".
One of them is that, whentaking a shower, you don't drop the soap.
Just don't drop the soap in the showers when Cort Strasser's anywhere close.