Cleaning the pipes is a phrase that is used to describe the act of masturbation in an effort to mitigate the effects of not having had sex for an extended period of time or before a date.
Cleaning the Pipes
More About Cleaning the Pipes
Cleaning the pipes is a way of allowing oneself to think clearly while not allowing sexual desires effect how one thinks. The idea is that cleaning the pipes of this sexual desire will allow the individual to think more clearly. This is why it is a common practice to clean the pipes before going on an important date. The phrase is, generally, used most to refer to male masturbation, but can also be used in reference to women.