The phrase, “What are you waiting for?” is so overused in advertising. I wonder who the first advertiser is who used it.
Many years ago, a company that runs a huge anime convention every year in Singapore, made a facebook post to tell their fans that tickets are now up for sale.
As you suspect, they ended the post with the words “What are you waiting for?”
And so I left a comment in that post saying “Waiting for the price of the tickets to fall.”
My comment soon got deleted and I noticed they stopped using these words again in future posts.