The GitHub Shop is offering a limited edition Atom mug, humorously described as potentially "radioactive," that coffee enthusiasts can purchase as part of a promotional deal on Cyber Monday, November 30th. Customers can enjoy free shipping on orders over $30 and a 30% discount on the Atom Mug, Octocat Figurine, and other items using the code OCTOCYBER2015. To ensure delivery by Christmas, international orders using Priority Mail International must be placed by December 8th, while domestic orders have a deadline of December 18th. This promotional event is highlighted in a blog post written by Brandi Firestine, providing details on the sale and shipping timelines.