OK. Red pill it is.
Here we go. Extra-terrestrial life forms have landed on earth. And they are not being kept at Area 51. Or any other government installation. Just look to the seafloor and you'll find proof positive that aliens live among us. Specifically nudibranchs. Take a peak at this National Geographic gallery of toxic nudibranchs and this article, wipe the drool from your mouth, pull your jaw off the floor, then return.
Nudibranchs are gastropods that have naked branches ("gills") hanging off their backs (hence the "nudi"), many with outlandish color schemes that appear to be a defense mechanism. But their alien characteristics are not just that they look stranger than anything that sci-fi has yet to produce. Some nudibranchs are Borg-like, assimilating weaponry and technology of other species into their own toxic arsenals. Many nudibranchs eat critters that have toxic weapons (stingers, nematocysts, poisons) then secrete the previously digested arsenal when attacked.
The 3,000+ species of nudibranchs are not content just to visit earth. Their super-secret plan for world domination includes reproductive cycles where up to 2 million eggs are laid at a time. And the option for hermaphroditic reproduction in some species.
OK, I'm being a tad over-dramatic with the Matrix allusion. And the course of your life probably isn't unalterably changed. But seriously, nudibranchs are some of the oddest creatures alive.
If, however, you do want to be creeped out by a Red Pill/Blue Pill experience, do some investigating into parasitic wasps, and your life will forever be changed. Not Exactly Rocket Science has some spine-tingling descriptions of these wasp species which must be alien. With the parasitic wasps, I'm exaggerating about the creepiness, but not much. Life is much nicer without the knowledge that, in the words of Ed Young:
Parasitic wasps make a living by snatching the bodies of other insects and using them as living incubators for their grubs. Some species target caterpillars, and subdue them with a biological weapon. They inject the victim with "virus-like particles" called polydnaviruses (PDVs), which weaken its immune system and leave the wasp grub to develop unopposed.
There is nothing so alien as life on earth.
10 Bonus Points if you tell me about other examples of alien life among us. I've taken the Red Pill already, so I have nothing more to loose. And so have you if you've read this far.