Penis theory is a catch phrase used when a male person does something, says something, or just behaves in a certain way that is attributable to nearly ALL men. These actions and behaviors are usually pointless, without significance, or increase stress or work and most females would never act this way. This phrase is most often used in a negative aspect by females in response to these frustrating behaviors exhibited by men.
My husband wont stop and ask directions: "Penis Theory".
The toilet seat is up: "penis theory"
Six trips to the grocery store due to lack of a list: "penis theory".
Speeding up and passing someone then slowing down in front of them thereby wasting gas and showing off: "penis theory".
Constantly flipping tv channels: "Penis theory".