When you are beating the meat, weedwacking, or any other variation of jacking off, and are about to bust but feel that the time is not right, or it is too early. Therefore you slow down to prevent the early yogurt shot and continue once the penis has calmed down slightly.
I had to slow jerk last night to prevent my premature busting problem.
A phrase used when something turns you off. Instead of being able to quickly beat it, your jerk gets slowed down because of a stupid comment or disgusting premise. Akin to an "eye roll" and often accompanied by a slow, masturbatory gesture.
Girlfriend: "We should totally see the Nutcracker when it comes to town!"