Let's drink to that...twice.
Everyone grows up with particular words and phrases that are not necessarily common to the masses. I have a dear friend, who uses the expression "chin-chin" as a toast whenever we get together to catch up.
I was not familiar with this phrase and never gave it much though. I attributed it to the wonderful lingo this friend has shared with me that I assumed was part of her idiolect; she often uses unusual words and expressions that she credits to her father.
I just recently learned that it is an interjection from the Chinese language.
Origin: 1785–95; < Chinese qǐng-qǐng please-please
So let's have a toast to Mexico for tomorrow's holiday...Chin-chin.
Happy Cinco de Mayo.