1 definition by Short and Curleys
Derived from the term 'bandwagon', it's used to collectively describe girls who back up one of their own for sometimes no valid reason other than sharing gender. 'On the Jam' is a vernacular phrase for being on ones period.
Bert: Kate told Donald she was on her period and couldn't have sex. Donald, hearing this, told her he didn't want her to stay over that night and left. Ellen called Donald a dickhead after Kate telling her this.
Ernie: Ellen jumped on the Jamwagon.Surprise Surprise
Ernie: Ellen jumped on the Jamwagon.Surprise Surprise
by Short and Curleys February 18, 2011