To slap someone across the face with one's penis.

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.

if someone happens to be getting fresh with you, mushroom slap them. This means pulling out your jimmy and making solid contact with their facial region.

Being slapped with a wang. Usually a hard wang.

When a guy takes his hard dick, and swings it as hard as he can, hitting a person (hopefully a girl) on her body with his mushroom. If done correctly it will leave a mushroom imprint for several minutes with a lasting red spot afterwards.

(not easy to do)