https://www.bluebikes.com/how-it-works/get-the-app

Enter promo code: BLUECARFREE in the app, valid Thursday, September 22 only.

Bluebikes is public transportation by bike and on Thursday, Sept 22, Blue Cross Blue Shield of Massachusetts is offer free unlimited 2-hour Adventure Passes for a 24 hour period. This will be available across the Bluebikes system’s 11 municipalities: Arlington, Boston, Brookline, Cambridge, Chelsea, Everett, Newton, Revere, Salem, Somerville, and Watertown.”