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!"
by Gorky's Zygotic Glove Puppet January 23, 2014
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