comes from a slang-language in the beautiful state of Hawaii called "Pigeon-English".
definition: safe - adjective used to describe silliness, stupidity, or ignorance.
Sometimes used in extreme sarcasm! Like "DUH!"
"Wow! Dat guy wuz so safe
, he couldn't even count da change, brah!"
"My little braddah, he act so safe
. He 35 years old and he act like one 2 year old!"
"I going to da store fo' one beer. You like one?"
response: "Well, yeah, safe