The Search for Extra-Terrestrial Intelligence. Most of our efforts along these lines consist of us sitting back, pointing gigantic dishes or very large arrays at the sky, and listening. Listening for some signal. A message from them.
But I bet there's some guy, some misfit, some rogue-minded individual somewhere on Earth who has taken a more proactive approach, and is sitting in his little corner of nowhere with a powerful radiotransmitter pointed at the stars pumping out a mathematically-coded challenge, broadcasting in all directions: "COME AND GET IT! WE ARE THE EARTH! WE WILL DESTROY ALL COMERS! YOUR CIVILIZATION IS WEAK! YOUR INTENSITY IS FOR SHIT! STEP TO US AND YOU WILL GET HANDED A PAN-GALACTIC ASS-WHUPPING!"
I think we better devote at least some of our resources to finding that guy, and shutting him the fuck up. Fast.