Every Minute on the Minute!
Every minute on the minute do 5 Burpees and 10 Squats. Rest the remainder of the minute. Repeat this for 15 min or until you can't complete the reps in the minute.
For a modified version, do 5 Pushups instead of Burpees.
For an advanced version, do 10 Burpees and 15 Squats. (It's tough, but possible!)