It's not really adult behaviour is it, and certainly not the behavior of a country that likes to think they are a world leader.
There are an increasing number of cultural messages, and messengers, in US media the subtext of which is "it is OK and even desirable to act like you are ten years old all of the time", the framing of Howard Stern as a folk hero being the canonical example.
I don't think anyone faults the fans of South Park, Howard Stern, etc. for finding them amusing. The problem is that immaturity is increasingly finding a place in public life. Apparently these soldiers think it's OK to act like ten year olds while acting in an official capacity, such that they don't see anything wrong with bragging about it to the media. It will be interesting to see whether their superiors think so too.
And, while this particular incident hardly qualifies as "torture", there does seem to be an immaturity continuum on the part of US actors and decision makers in the Iraq war that starts here, runs through Abu Ghraib, and all the way up to the White House, where apparently torture was not only planned and condoned, but micromanaged, with high level participants apparently doing so at least in part to gain personal satisfaction from the act. There's no credible evidence that any of it was effective, and plenty of evidence that it was counterproductive, but apparently, in times of crisis, the appropriate response is not to act like adults and address the problem effectively, but to act like ten year olds and pull the wings off of flies because we can.
And, while there has certainly been a fair bit of outrage over all of this (underreported) in the US, there are plenty of people who thinks that it is all right and good. It would be interesting to know the correlation between South Park/shock jock/reality show fandom and the condoning of torture among the American public.
But don't get too cocky in your own country. One of America's biggest exports is its media. It's like I tell my kids: what we are, you will be. ;-)