-tbh (to be honest): same inquisition as the one above applies. Lying cunt.
-if I'm honest (tbh's cousin): What do you mean if? So you're really not honest? If, in a hypothetical alternatve universe, you were posing as an honest man/women/cunt, this is what you would say. However, since you are a lying gobshite cunt, we should assume this is not what you really think. Lying douche.
So which one of these phrases is the most superfluous, pointless and useless?