It's said that it was used by dockers in Hamburg for the first time and was later adopted by the Hamburger Hip-Hop Wave in the early 90s!
It has the same meaning as the English "mate", "dude" or "bro" depending on the context!
"Ey Digga, was geht?" - "Yo dude, what's up?"
You'll never rid us Diggaz even middle finger wiggaz with us, chilled sick ass diggaz rip it up...