D'poi is pronounced da-poy, meaning div, divmo, anything where you have been a bit thick and need to be insulted or told because of it. it can be said as D'poi, or spelt out in the style of a song, "D, apostrophe, p, o, i"!!!! great fun!
jim bob spilt wine on franks rug, frank shouts at jim bob "jim bob you stupid bloody D'poi"
if you were reminding someone of their stupidity and it was quite ammusing, you would then do some thing like this: "ha, ha, mcfro fro, you stupid d, apostrophe, p, o, i!" (in a singing voice)
the mofo-ist, jones-ist, mofo in town. mofo Jones is what you can call a mate if they have been a bit crap to you. its a form of friendly insult, the kind of insult that won't upset the other person, but will make them aware of their stupid actions.
so if someone forgot to do something important, you could say "oh no, mofo jones" but only if its a friend, if its someone generally crap then please feel free to use real nasty insults.