The boner that a termite has when it gets a boner in its pants.
Gee, that termite sure has a huge termite-boner!!!
The intense climatic feeling of exhilaration encountered when stimulated beyond arousal of the intellect; a hyper-focused state of mental masturbation.
He / She's got a Brain Boner for it, I can't believe how long he / she's been {watching, reading, listening, etcetera} this.
An idea.
I had a raging brain boner the other day. Space Suits for cats is a good idea, and don't let anyone tell you otherwise.
When you flip the side pockets of your pants inside-out creating a penis looking shape which is referred to a "side boner".
Speaker 1: "Hey, why do you have a side boner?"
Speaker 2: "Oh, I must've gotten it when I was searching through my pockets looking for my keys."
When a male sees something sexually stimulating, but isn't able to achieve an erection due to a previous orgasm
Guy: "Darling, you're so sexy. But I'm only able to get a ghost boner right now."
Girl: "Those gosh darn ghost boners!"
The act of pulling youre strong boner all to one side and then letting it go, so its swings around.