Ripping a tendon

It is a euphemism for masturbation

"Ripping a tendon with the boys"

Past Tense: Ripped a tendon
Future Tense: Rip a tendon
Present Tense Ripping a tendon

Codie: Hey Larry, dont come in my room for the next 20 minutes ,I'm doing schoolwork

Larry: As if, it's summer. Are you ripping a tendon

Codie: yes..

Larry: Can I Join?