When having sex doggystyle, the male inserts a thumb in the anus and turns his hand to resemble making a turn while driving a bus.

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.

To throw up into a toilet, with a death grip on the toilet seat at the 9 and 3 position as if it were the steering wheel of a bus. Most commonly done after drinking excessively.

The act of having sex doggie-style, where the man's hand is resting on the female's lower back or upper rear-end. The combination of the two often results in a motion which resembles using the large steering wheel on a school bus.

Holding onto the toilet bowl while vomiting. Also known as "driving the porcelain bus".

To unintentionally drive a common route. To turn on the mental autopilot and arrive toward a location other than your desired destination. For example, if you set out to drive to the store, but after a few minutes find that you are halfway to your place of work.

Vomiting while kneeling and holding onto the rim of the toilet. So called because it resembles grasping the large horizontal steering wheel of a bus.