The art of concealing one or more rusty nails inside of a baked good, such as pie, followed by smashing the pastry into a friend or foe's face causing them excruciating pain, via nails in the face, while bringing wholesome joy to all witnesses. (Remember, it has to be a pastry/baked good or it wont work)

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.