It looks like she dry-heaved right when she realized.
She just got hit by a smooth criminal.
The best part is imagining them choreographing this together beforehand, with him making sure he'd have a chance to do this, getting her to slowly turn around, and her none the wiser.
He was just getting a piece of gum.
This made me smile.
During the first move you can see him check his back pocket to make sure it's still there (and hold it in place maybe)
That one girl in the back, sitting down, realises significantly earlier than anyone else.
The kids got excited so fast. They all know about this position for proposal.
"Pam, will you... wait for me to tie my shoe?"