French Dollar
A french dollar is when you have sex with a woman in the ass with such force, that you break the barrier between the ass and the vagina, making a hole roughly the same size and shape as a french dollar coin.
I once had sex with this girl who was so tiny, I ended up french dollaring her.
French dollar
To pay for something, using a french kiss as a currency.
We'll watch your favorite movie if you give me 5 french dollars.