1 - The end of the (outrageous) British discount
"I want my money back."
2 - New customs agreement profiting to the EU
Brexit would mean the end of free trade and the implementation of new customs agreements.
3 - Relieving Calais
Consequence of the previous point, the free movement of European citizens would also mean the end of the Calais camp, as passages won't be controlled anymore between France and the UK.
4 - Let's make Europe clearer
"The agreement concluded on the 20th of February opens the door to an "à la carte" Europe where countries can opt for a deeper integration if they want to."
5 - We'll steal your City
This is probably the best outcome of all: many banks are considering to relocate some teams in Paris, Dublin or Frankfurt if Brexit happens.
6 - A bit of English bashing...
They love to hate us.
64 million English speakers out of Europe isn't nothing.
7 - Vive la Francophonie