basically, hysterically crying. or just crying really. doesn't have to be hysteric.

Term used by working musicians referring to time spent alone practicing and getting better. Practicing "in the shed" so to speak, i.e. not playing gigs in front of people for a while so you can work on your chops. Often this is ti me spent learning scales or theory or working on technique.

Reffering specifically to musicians
but can be used for any subject

Sheddin' is used to describe an evolution of skill or to practice to another level of skill

To spend time in a shed, shop, garage, or other external building performing odd tasks. This activity is commonly performed while consuming alcohol.

"Sheddin" a term that is commonly used among musicians that in some circles may be referred to as a "jam-session". Sheddin is underground music jargon that artists use to reference a gathering of musicians.

gettin high in a shed

also see dockin' or deckin'