Definition:
A sandwich.
Usage:
I could really go for a fried-egg-and-chili-sauce butty right about now.
Explanation:
Butty comes from the fact that sandwiches are often spread with butter.
Trivia:
Some non-Brits have learned this word from the British TV show "Red Dwarf", where the character Dave Lister has a fondness for strange butties.
