An ordeal that lasts a short amount of time, but requires a great deal of skill and concentration to successfully manage, especially near its completion.
Named for the climax scene of Star Wars Episode IV: A New Hope.
"A week of exams with Physics and Calculus on the last day; that's one hell of a trench-run!"
Esp. with a large woman, lay the pen0r between the ass cheeks and masturbate with them. Just before you ejaculate, say "Use the force Luke", and then spread and aim for her exhaust port.
Extra points for painting the pen0rlike an X-Wing and your balls like Tie-fighters.
Deduct points if you bullseye her "whomp rat".
"I did a trench-run on Lisa last night, she growled like a wookiee"