Meaning eccentric, daft, insane, crazy, not quite right in the head. Etc.
Originated from England.
You're bloody barmy. You know that right?
adj. 1.) extremely silly
2.) One who is extremely silly
1. "It's plain barmy of you to think he is a still a virgin at 22!"
2. "Oh, nevermind Sarah. She's not all bad, she's just barmy."