Though 'Rectum' and 'Erection' are two completely different things, they have been known, particularly by the Greeks, to fit together like hand in glove.
Also not to be confused with a plectrum. It can only end in tears. Trust me on this.
Don't even think about confusing it with your philtrum.
It has a strange resemblance to Rector and Donald Trump.
All shapes that are not rectangle or cirtangle can not fit into your rectum because of electromagnetism. It's been proven by science, comrades.