Drake's equation, especially when you extrapolate it to billions of galaxies, makes the idea of Earth being the only place to have life as being conceit of the highest order. That said I don't think they've been visiting to anally probe drunk American farmers and tip over cows (WTF sort of racist bullshit is this anyway? Are Australian farmers puckers not up to some intergalactic standard? And Australian Beef > US Beef).
Can't blame the aliens they've probably seen deliverance and thinks thats how American farmers say g'day.