Created accidentally when a student started to speak with the intention of saying "to be fair" changed mid-sentence to "to be honest". The resulting speak was "to be fonest"
Can be used to take the piss out of someone, completely under miming what they have just said. Or to diffuse potential life and death situations, eg. an encounter with a hungry lion.
(abbreviation for instant messaging geeks: tbf)
Mum: James, I think drinking a bottle of frostys a night is a bad idea...
James: Mum, to be fonest, you're a fuckin' idiot.
Mufasa: Roooooaaaaaarrrrrrr (I'm gonna kill and eat you)
Antelope #1: I taste like shit... to be FONEST
Mufasa: arf arf arf
Antelope #1: fancy a beer and a game of snooker later?
Mufasa: aye sound nowt too shabby man...