Jerking

When I was a kid I was jerking off in my room, and my mom came in just right at the moment when I was coming.

Sami was jerking.

Sami was jerking off behind Layla.

He was jerking off.

I'm jerking off.

You don't have to resort to jerking off. You've got your girlfriend.

Tom made a jerking motion with his hand and blew a raspberry.

"What effect do you think it'll have?" Tom asked John, who made a jerking motion with his hand and blew a raspberry.

The 'movement' was simultaneously emotional and motoric, and essentially autonomous (thus distinguishing it from passive jerkings and other pathology).