On your J's

On your own, by yourself.
From cockney rhyming slang, 'Jack Jones = Own'

My friends were busy, so I went to the movies on my J's.

Who wants to go to the museum today?
Not me mate, you're on your J's.

by hoaretom October 22, 2008

Being on your j's

Being alone
Being by yourself

"We don't like you being on your j's, so we'll just come with you."

by Samuel Billy Bob Smith March 15, 2009