Used to describe an erection that you get from something that you never expected would give you an erection. Puts an official name to the infamous "surprise" boner.
Alternate definition: An erection that one WILL receive while watching Apollo Anton Ohno speed skate; it's inevitable.
"It was the weirdest thing. I went to flip the light switch and the static shock gave me a raging Oh-Noner. I had no idea I was even into that stuff!"