We had
"EMERGENCY, GRAB YOUR ANKLES"
then
"HEADS DOWN, STAY DOWN, BRACE, BRACE"
and then with the introduction of lie-flat beds
"EMERGENCY BRACE"
Strangely enough, no standardised commands for evacuating, although I do remember singing "waiting, waiting, slide inflating" haha...
My current employer is much more by-the-book (and the book is larger!)...