One of the most radical for me was Cambridge to Stansted, relocating a PAX MD11 from a MX base with a short runway to fuel up for a longer flight. The boys driving set high thrust with brakes set, I was firmly put back in my seat when they kicked them off. I had the bird's eye view in the cockpit. Lots of fun and the shortest flight I ever had, think they said 9 minutes.
Another fun takeoff was in an empty MD11F with about 50k LBS of fuel and no freight, the pilots this time just wanted to have fun. After rotation we leveled off a bit allowing for airspeed, as they rotated the 2nd time I remember seeing 45 to 50 degrees nose up, had to fight the Gforce to keep my eyes on the instruments (PFD). Fun times as a flight mechanic I will never forget.