For ORBISON you'll need a stopwatch. Every 60 seconds you perform 4 Burpees, 6 Squats and 8 Sit Ups as quick as possible. Repeat this 20 times, every minute on the minute until 20 minutes (EMOM 20) have passed.
Example: If it takes you 40 seconds to complete 4 Burpees, 6 Squats and 8 Sit Ups, you have the remaining 20 seconds to rest until next minutes starts.
Scaling: You can scale ORBISON by reducing the repetitions by half and therefore extending your rest times