In gaming culture, smurfing is defined as logging into a secret account seperate from a main account as to allow the user to play a game without being detected by his or her peers.

Generally the purpose of smurfing is to improve oneself without compromising the statistics of a main account. It allows gamers to try new strategies, or simply play without worrying about a "record".

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.

Gaming term: Entering your regular server under a different name so u can see whats going on without being recognized.

Commonly used by server admins and the like.

Attempting to hide your identity from administrators and peers by creating a secret account; in gaming culture, this often occurs after being blacklisted under a previous name.

Purchasing small amounts of pseudoephedrine in several stores or by groups of people, with the purpose of using it to make metamphetamine.

Buying up the maximum allowed quantities of pseudoephedrine-based medicines at one location after another for use in the production of crystal meth.

Verb:
In forum usage, the act of a person using another login name to try to fool the forum populace that he/she is a different person. Usually occurs when the said person was recently blacklisted under a previous name, and is attempting to cover up or hide his/her new identity.