Jack-off double feature - You slap your dong twice in a row like it's a math problem a

You slap your dong twice in a row like it's a math problem and you're trying to solve it.

I did a jack-off double feature because I was bored out of my mind.

He did a jack-off double feature because he had no internet and no friends.

She did a jack-off double feature because she had to finish her homework and it was the only way to survive.