Definition:
The Act of a Songwriter or Anyone Lyrically "Killin-The-Beat" by Writing-Rhymes or writing Historic-Bars in a Nonstop manner. Utilizing the following to do so: Pen & Paper, PC, or via Cell phone one nowadays.
PimpThePen.com

History Behind PIMP THE PEN
The term derived from back in the late 80's when Hip-Hop MC's or Songwriters Wrote their Lyrics, Verses & Rhymes down on Paper with of course a PEN and specifically more-so in the South, like H-Town Texas (SUC Legends) such as the DJ Screw, Lil Keke & Lil Flip era. Per the well-known Verse on the song PIMP THA PEN and STILL PIMPING PENS Mid 90's Early 2000s Thang.

Therefore, most people ( generally) wrote Lyrics on "PEN and Paper" -and many still do today, but with Technology Advancements the term keeps the same iconic meaning & is well understood. Last thing to note, if Pimping means Working-a-Woman So She Can Make Money For You. Then, hopefully, you can comprehend the Meaning of Pimp Tha Pen same thing with Pimp These Beats, etc. -Simply a phenomenal Metaphor in this case "Pimp The Keyboard" since we in 2020 vs 2000'. -and Not in Reference to prostitution,

The Term Also Represents;

Music Industry Artists, ScreenWriters, Authors, Bloggers Editors. to Flow on (Rap/Hip-Hop).The Slang-term Applies to "All Genres of Music or any Style of Writing.

The act of extreme masturbation. You must "knock one out" whilst in close proximity to any of the following; Your mum, a nun, your boss, a member of parliament, George Michael. A person with capabilities to act upon catching you mid self-abuse obvisouly ups the ante. Ejaculation must be reached before your danger wank target comes (no pun intended) to investigate. The higher the chances of being discovered with one's pants down, pulling one's war face is obviously where the danger comes from. The more danger involved the harder (or softer) it is to complete the task in hand (snigger). The more dangerous the better. The chance of being arrested, pummeled by an angry father or having your hand severed by an arab's sabre means that you are a pro "Danger wanker."