So there's a few people that have some trouble with the abortion QTE, when they play Stick of Truth with Keyboard & Mouse, so I thought I'd type out how I did it, and keep doing it consistently.
Make sure you read ALL of the instructions for Phase 3 BEFORE you start it, that's the tricky phase

Phase 1: Follow the instructions as presented to you. (IE. Left click when the needle is directly over the balls - but only click, don't hold)

Phase 2: Again, just follow the instructions. (Mash A & D)

Phase 3: When the vacuumtube is on the left side, HOLD left MB and then CLICK right MB when prompted. After that, the tube will switch to the right and you HOLD right MB and then CLICK left MB when prompted. If you've done it correctly, it'll switch over to the left side again and you just HOLD left MB and CLICK right MB when prompted, that should perform the abortion and the event should be over and you can progress your story.

You've now successfully aborted something from Randy's, uhh, scrotum.

I hope this helps anyone that is struggling with it, as I feel the explanation from the programmers side is sub-par.