Originally from Battlefield 1942, also seen in subsequent Battlefield games featuring aircraft.
While being pursued in a dogfight, the pilot will pull up sharply into a 90 degree vertical climb. He/she will then exit the aircraft (his/her velocity will cause them to travel upwards alongside their aircraft for a short time). The pilot will equip an RPG / SMAW and attempt to shoot the pursuing enemy out of the sky before climbing back into your aircraft and continuing flight without stalling / crashing. (Note: You must be the Engineer class to equip Rocket Launchers)
A perfect (and hilarious) Zooking example
Youtube; Search : 'Rendezook'
Nice work dude, you make it look easy