Mile Low Club 

The opposite of the mile high club, where the requirement for membership is to have sex below the surface of the earth. Also applies to submarines.

Guy #1: I heard he went spelunking with his girlfriend last week. Apparently he joined the Mile Low Club.

Guy #2: Aww yeah I'd explore her cave alllllll night long.
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Nazi Soldier #1: U-Boat 96 just got back. I heard the captain joined the MLC while they were at sea, chicka chicka yeah chicka chicka.

Nazi Soldier #2: Nasty dude, that was an all-male expedition!

Mile Low Club by arrivez à l'helico February 11, 2010

Mile Post Club 

Getting it while on a train. The railroad version of the Mile High Club. Taken from the term "mile post," the railroad equivalent of highway mile markers. Applies to intercity and commuter trains (Amtrak, Metra, Metro North, etc.).

1. I joined the milepost club on the Amtrak train to New York last night.
2. Sex life dull and boring? Try riding the train and joining the mile post club.
3. You've banged 3 girls on a plane? Well, I banged 7 girls on Amtrak on one train trip from New York to LA. The benefits of being a member of the mile post club.
4. I never had time to pursue my sexual fantasies before I joined the mile post club. Now I get it every night on my commute on Metra from Chicago to Homewood.

Mile Post Club by Lumberjack93 May 26, 2011

Mile Under Club 

The act of having sex in a submarine.

You: Dude i just joined the mile under club.
Friend: You mean mile high club?
You: No, i fucked in submarine bro.

Mile Under Club by R3FRACION October 10, 2011

Mile Five Club 

Jerking off in an airplane bathroom.

I saw this hot chick on the plane when I was on vacation. I was too much of a pussy to talk to her so I went to the bathroom and joined the Mile Five Club.

Mile Five Club by monkeyboy2 March 5, 2010

Mile deep club

The hardest of all the "mile clubs" to get into, to get in, you have to have sex in a submarine, a submersible, or a bathysphere.

Richard: FUCK YEA!
Mike: what?
Richard: I'm now a member of the mile deep club!
Mike: what the hell is that?
Richard: Its like the mile high club, except you have to have sex in a submarine.

Mile deep club by Dr_dude January 10, 2015

The Mile High Club 

Having sexual intercourse of any type inside and airplane. Usually considered to take place in the lavatory.

Follow me into the bathroom big boy and we'll join the mile high club. http://www.themilehighspy.com/content.html

The Mile High Club by The Mile High Spy October 16, 2008

Solo Mile High Club

In comparison to Mile High Club, this is just the same except doing it solo. In other words, masturbating on a plane.

Also known as Half Mile High Club

Jono: "Argh! This 55 minute flight is lasting forever! Guess I'll go join the Solo Mile High Club."

Solo Mile High Club by Techn1x December 28, 2008