Similar to a bogan, a yobbo, a hooligan, someone with no style or class, or a person with a beer belly wearing stubbies holding a beer and talking with a thick accent.
eg. someone does something stupid, you say "you are a bogo"
Twins. A reference to a Buy One Get One sale, two offspring for a single act of coitus. Can be used to refer to identical or fraternal twins; male, female, or both.
Phil: How old are Nancy's kids
Steve: Seven.
Phil: Oh, they were BOGO?