I'm going on holiday to America soon, i was just reading the TSA Rules when suddenly i read the following:
"While wrapped gifts are not prohibited, if a bag alarms our security officers may have to unwrap a gift to take a closer look inside. We recommend passengers wrap gifts after their flight or ship them ahead of time, to avoid the possibility of having to open them during the screening process."
So now i'm just imagining this giant TSA manchild looking at a monitor all day looking for wrapped presents. Getting all excited if he finds one and has to unwrap.