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)