Short for the whole phrase that Dutch (played by Arnold Schwarzenegger) says in the movie Predator, which goes:
"RUN! GO! GET TO DA CHOPPA!"
This can many any number or things, or mean nothing at all.
Frequently it is used when something exciting is happening or will happen and they need to be going someplace. It's used when there is no need to mention where you're going, you all already know where you're going. So you just yell GET TO DA CHOPPA!!!!
Friends get in their seperate cars, about to leave school and meet up at the diner, but before leaving they roll down their windows and one yells "GET TO DA CHOPPA!!" before they all speed off.