It's a move used during a roller derby. Specifically, it is when a skater grabs a teammate's hand/arm and is pulled forward, "whipped" around and in front. It builds speed and helps her get through the pack.
Bliss' t-shirt (which once belonged to her mom) is for a band named Stryper. Stryper was a successful Christian-glam-metal band, playing from the mid-to-late 1980s to 1992, with a reunion in 2003. They have an official website.