A natural repellent that certain females tend to excrete. It causes males to be driven away from said female, resulting in her lack of sex. Examples of penis repellent are but are not limited to: being but ugly, smelling like rancid pussy, or even if she is the sexiest person you've ever seen, she may be a total bitch. That alone qualifies as instant penis repellent

The safeguarding of Earth and other worlds from biological cross-contamination (i.e. billionaires with too much time on their hands).

Also known as “planetary protection.” Planetary protection / quarantine “reflects both the unknown nature of the space environment and the desire of the scientific community to preserve the pristine nature of celestial bodies until they can be studied in detail.”

There are two types of interplanetary contamination. Forward contamination is the transfer of viable organisms from Earth to another celestial body. Back contamination is the transfer of extraterrestrial organisms, if such exist, back to the Earth's biosphere.