> their quest for world domination will remain completely hidden from us until the day they actually take over ...

The time to worry is when you hear them whistling The Star-Spangled Banner while performing a backwards somersault through a hoop. When that happens, get the hell outta here, double-quick.

Or whistling God Save the Queen while wearing a T-shirt emblazoned with a map of the old British Empire! (and a sailor's cap with "English Fleet" stitched in front)