za Urban Dictionary :
1. Safe as Fuck
extension of safe, used by hardcore welsh gangster rappers the GLC. meaning that is 'cool as hell', 'really rather fabulous' or can be used as a farewell.
2. Safe as Fuck
Used by the ever growing Chav culture in England to describe an object, event or doing of something to be realy great. Often spelt Safe as, or Safe as fuk.