Terribly Trembly Tummy

I've got a terribly trembly tummy
I know it sounds it, but it's really not funny
I can't stop my hands from shaking
About this part I'm meant to be playing

I'm not sure how I volunteered
It's not something I'd normally go near
But somehow I'm standing in the wings
Trying not to forget everything

Which word is my cue to come on?
What are the right notes for that song?
Am I meant to smile or frown?
Please don't let me fall in this gown

Wait,  I think it's me next
I'm imagining them all in their vests
Wish me luck as I take this huge leap
Oh ...... phew, it was a dream in my sleep.