Double Bubble activity is perfect for revision or review of a topic / argument etc.. (tes.com)
Carrozzeria Zagato built a small series of coupés with the unofficial designation of 1900 SSZ, designed for racing with an aerodynamic lightweight aluminium body and Zagato's trademark double bubble roof. (en.wikipedia.org)
On the other hand, a win vs top 4 seed seems to count as much as double a bubble win, and a road win vs a top 4 seed, seems to count as much as say 3 wins or more. (sbnation.com)