Hiking in the Appalachian Mountains 

Claiming you are going "Hiking in the

Appalachian Mountains" for vacation when in fact you are going away for a booty call.

Bob: Yeah, I'm burnt out. I'm going Hiking in the Appalachian Mountains for some R&R.

Frank: Dude, who are you kidding. I saw you and Sally from the copy room groping each other in the bar. You're headed to a Motel 6 for a few days

Hiking in the Appalachian Mountains by Langbo June 25, 2009

Hikin' the Appalachian Trail 

Cheating on your wife or girlfriend, especially if in the process of cheating, you disappear for a few days and say you are going someplace where it is impossible to be reached. Can also be used on a woman to say that she's cheating.

Same meaning as the other two entries here at UrbanDictionary.com: "Hiking in Appalachia" and "Hiking in the Appalachian Mountains", except that that "hikin' the Appalachian Trial" sounds better.

guy 1: "Where's Dave? I thought he he was going to play golf with us today."

guy 2: "He told his wife he had to work the weekend, but I think he's hikin' the appalachian trail. He was flirting all week with that new chick in accounting"

-or-

guy 1: "Where has your girlfriend been lately?"
guy 2: "I dumped her ass! Caught her hikin' the appalachian trail, and that was it for that slut!"

Hikin' the Appalachian Trail by rpompeii June 29, 2009