When you gotta take a big shit, and you drop it all in one steamy log, rather than many shits. Its glorious and sought after by many cultures. Some say it's where the term "holy shit" derives from. A one-logger must be chosen by God, and cannot be artificially induced, thus banning the faux-logger.

(noun) A successful type of theft which results in an acceptable, impressive and rewarding payday for the protagonist.