Robin Williams plays Lance Clayton, an aspiring but rejected writer (ironically the 'World's Greatest Dad' of the title) the who teaches at the same school that Kyle, his son goes to. His son is a mean spirited, selfish, porn obsessed prat who pours scorn on everything, including his downtrodden father. However, after Kylie accidentally kills himself while practising Autoerotic Asphyxiation (badly), Lance adjusts the scene to make it look as though he had hanged himself, and writes a fake suicide note, in which he (supposedly Kylie) rages against the fakes and phonies. This is a smash hit with other children at the school when it is posted by a pupil on the internet, and Kylie becomes a saint like figure to them. Lance then writes a fake journal in his sons name, which is also a smash, whereupon it all starts to get really out of hand. When a library at the school is to be named in Kylie's honour, Lance eventually faces up to what is happening, and cracks. It's a black comedy with not a lot of laughs, but worth watching, especially if you don't mind lots of potty mouthed language (which l don't). If you do - avoid this, as there is plenty of it.