We have it on good authority (well, the internet movie database at least) that Bananas in Pyjamas premiered in the summer of 1992. However, it didn't reach these shores until at least the mid-1990s.
Sean O'Brien was born in 1987. Therefore he would have been around eight or nine by the time Bananas in Pyjamas hit our screens. Much too advanced for that kind of fare.
Still, in deference to his nephews, he donned the pyjama suit to mark Halloween last night.