OK I am starting a weapons category now. This is scary, the gent from the slingshot channel took up Bill Gates challenge for a better condom (100,000 G prize) and created a slingshot to put one on…I think this would work well as a birth control either way.
http://gizmodo.com/5994008/this-terrifying-condom-slingshot-is-the-most-effective-birth-control