When you're a hammer, everything looks like a thumb. Edward Teller had a hammer, and every problem he encountered, his first thought was, "How could I use a thermonuclear weapon to solve this?"
Teller once proposed to map out all the dangerous asteroids in the solar system, the ones that might someday cause major damage to Earth. He suggested that a thermonuclear explosion on the far side of the Moon could generate an electromagnetic pulse that could be used as a radar pulse, with returning echoes showing even small asteroids.
In "The Day of the Dove," on Star Trek, The Original Series (as it is now known), an alien entity sets up the Enterprise as it's own personal negative emotion larder, pitting humans against Klingons in an eternal battle, meant to supply it with "negative emotions" which the alien eats. Hey, this was as good as it got on Third Season Star Trek. One interesting point in it was that the alien healed the wounds of anyone injured in the battle, making the entire endeavor a lot like the legend of Valhalla. The Klingons, at least, should have dug the setup, but apparently didn't like being manipulated, the ingrates.
If a single starship's worth of humans with negative emotions was enough for one of the creatures, imagine how many there are floating about Earth. One can only imagine what ancient atrocity sent a big enough pulse of brutality and pain out into the void, announcing our presence to that particular race.
Still, fear and anger aren't the only foodstocks, I expect. We have such a variety here. As time went on, I imagine that either the aliens developed other, more refined tastes, or different aliens, with different needs, came upon our little emotion laden treasure trove.
I'm not sure if irony is an emotion, but there is little doubt in my mind that the irony eating aliens are here. Perhaps we first came to the attention of the sarcasm lovers, sarcasm being the most fragrant form of intentional irony. I would expect that those guys showed up sometime during the height of the British Empire, the British being such masters of sarcasm. Irony, of course, is more subtle, but potentially more nutritious, if prepared correctly.
The most essential form is Unintentional Irony, of course. If we had not already come to the attention of the UI connoisseurs, I am sure that the giant pulse of it that occurred with the award of the 1973 Nobel Peace Prize to Henry Kissinger alerted them to the rich lands awaiting their arrival.
So, without further ado, here you go guys. Chow down.