Definition
To engage in an extramarital affair.
Origins
Referring to the excuse given by the spokesperson of the former Governor of South Carolina Mark Sanford during his disappearance from June 18 to June 24, 2009. Upon returning from his absence, Governor Sanford gave a press conference and confessed to having travelled to Buenos Aires, Argentina, to visit a woman with whom he had been having an extramarital affair.
How People Actually Use It
To have a sexual encounter or affair, named after the infamous disappearance of South Carolina Governor Sanford, originally thought to be hiking the Appalachian Trail, but was having an extra marital affair in Argentina.
"I wanted to Hike the Appalachian Trail in the back seat of my dad's Lincon after prom, but my date wasn't drunk enough."
Source: Urban Dictionary