Jumping on the revealing post bandwagon
I knew they were aliens because they talked and I could almost visualize the triangles and wavy lines of their speech. I was 10 and 4/12 years old and I was riding my bike really fast through my neighborhood because there were kids with sticks trying to crack my young innocent skull. In fact, I was riding so fast I didn't see the spaceship in front of me and I rode ride up the ramp and into the bowels of the ship.
I don't remember what the aliens looked like. All I do know for sure is what they didn't look like. They did not look like frogs, hotdogs, roses, Rod Carew or any of the Beastie Boys. They didn't probe me either but they did test my eyesite. The strangest thing to me was the apparent excitement they displayed when I crossed my eyes when they brought an object close to my nose. They made me do it so much that I got a headache and started to cry.
After a couple of hours they let me out in a park a few blocks from my home. The kids that were chasing me earlier were there throwing rocks at seagulls. As soon as they saw me stumble out of the bushes they chased me down and beat me up. The fuckers.