It's a speed-up software for Linux developed by Linus Torvalds and who called it "Git" after the British slang word for an unpleasant person in homage to himself.
What does 'Git' stand for?
In the south (southeastern US) people say Git as another way to say Get. Not sure if that's the same Git your talking about but if you were to ask that question to anyone around here, that would be the answer you'd get from most if us.