The aliens made their base on the Moon and silently watched the Earth, never making contact. They disguised their technology, and hid their signals, disappearing into wavelengths we couldn’t detect.
Eventually Humanity took its place amongst the interstellar civilizations. But Terrans couldn’t help but notice how aliens always seemed weirdly embarrassed.
Eventually, a junior delegate got the truth out of her opposite number at a peace conference. “We set up a watch post and observed your civilization for centuries,” he admitted.
“For science?” She asked. “Or because we were a potential threat?”
His three eyes wouldn’t meet hers. “For comedy.”