Sex bolts.

For Valentines day, I got to go to the store and buy some sex bolts. And I have to admit, my inner twelve-year-old is taking inordinate glee in letting folks know I have to do that. *giggles*

Yes, they are a real hardware item, Also called chicago screw or barrel nut.
http://en.wikipedia.org/wiki/Sex_bolt Used for certain specialized applications, where you want something like a rivet, but need to be able to unfasten it occaisonally.