Are There Butterflies In Your Stomach?

What is it about CrossFit workouts that make your stomach feel all funny?  The anticipation can create some poignant butterflies.   Here is the 8am class right before the second part of today's workout. 

Workout:

7 minute AMRAP:
10 handstand push ups
5 squats cleans (175/115lb)
- 5 minute rest -
7 minute AMRAP:
2x:  5 pull up 10 push up 15 squat
6 hang power clean (105/155lb)
- 5 minute rest -
For time:
40 burpees
40 toe to bar