When I was in the Navy, during the mid 90's, I watched these things take off and do training tests or whatever they did. We watched them for hours. It occurred to me, watching them in perfect daylight and with a understanding of what I was watching, that if I didn't know what that was it could have easily been a UFO. And ever since then when someone tells me that they might have seen a UFO I tell them about watching that airplane and how UFO it looked taking off and doing maneuvers. Its shape and speed make it such a bizarre thing to see.
I saw some jet in 2010 at an airshow in Spangdahlem, pretty sure it was an F-22, transition from flying normally to what can only be described as standing on it's engines and flying through the air, horizontally, belly first. Evidently this was easy enough to be performed directly over the base at a very low altitude. Mindblowing.