i'll give you 100 dollars
A promise from a fake rich person who says she'll pay you if you do something stupid.
She said she'd give me 100 bucks if I kissed her dog. I did. She had no money.
She dared me to wear my socks on my hands. I did. She said she'd give me 100 dollars. She had no cash.
She said I'd get 100 dollars if I ate the whole cake. I ate it. She had no money.