A common euphemism for having sex/having an affair. This term was popularized by Governor Mark Sanford of South Carolina, who went missing for several days and informed the public he was hiking
Verb. When camping, 'hiking' is a way to describe to elderly or very young relatives what underage teens are supposedly doing when they are not at the campsite. typically used when said teens are out in the woods enjoying activities involving alcohol or pot.
grandma asks, "where's so and so? We're about to make s'mores."
Hip older cousin replies, "oh, they're out 'hiking'."