1.One who acts in an odd manor, often due to OCD.
2.A true genuine weirdo, not someone who tries to be a bit "whacky".
1."That oddigun over the road fills milk bottles with his own piss and stores it in his lounge."
2."She had her dead mother stuffed and keeps her in her conservatory"
"Wow! what an oddigun."
"You should see what she's got in the kitchen."