Some people still seem confused about the meaning of the term "Gate" referenced by Hanksy Pantsy so I have included a cap.
I first heard the term in a Derek and Clive sketch (Peter Cook and Dudley Moore), which made it's use self explanatory.
Peter Cook was talking about having himself filmed whilst masturbating and ejaculating into his navel as if it was some great accomplishment. It was discovered that there was a hair in the gate and the scene was then thus ruined.