I believe most US insurance companies will not cover a colonoscopy for those under 50 unless there is a specific reason (family history, polyps....)
I did wake up right in the middle of mine, it hurt somewhat but was not excruciating. I felt like Jets Things when he pretends to be wasted and unconscious in a gay bar bathroom.
When I came to I said, "Hey, I thought I wasn't supposed to wake up". Dr. said "you didn't tell me you had a crooked colon or I would have brought my crooked stick" Doctor and nurses chuckled. I was squeezing the rail of my bed and looking like I was trying to pass a bowling ball. I then eventually passed out again.
It wasn't the end of the world. I wouldn't do it again for fifty bucks....maybe a hundred.