If people are looking at you like a psycho killer, I think it's probably for some other reason than you saying "see something once why see it again?". Were you holding a very large knife when you said it, perhaps?
David Byrne was lead singer for a band called the Talking Heads, and they had a song called Psycho Killer. One of lines in the song is “say something once, why say it again?”
It’s a pretty obscure reference and I did not get it when I made my initial response.
