What is Galah?
1.
An "Old Australian" word; an derrogatory term that means a "loud-mouthed idiot." Named specifically for the galah, a native Australian bird that makes a distinctive (and quite funny-sounding) call.
"Oh, Scotty, ya bloody galah! What are you ON ABOUT?!"
See
2.
A real fool. Often a fool that spends their time jabbering.