Carriaging is the act of standing between carriages on a train, one foot on either carriage, feet a little more than shoulder width apart standing goofey or regular. Relatively loose trousers should be worn but not too loose so as to allow just enough room for your penis and balls to swing side to side as the carriages move against each other. If the clothing is too loose you wont feel the essential rubbing of the tip of the penis against the clothes to fully enjoy Carriaging.
Although usually just done solo with clothes on and just for fun to entertain ones self and friends, it is also possible to carriage naked but then you will need a friend or other object to carriage on. You can naked carriage on somebody's face, breasts, ass or any other body part but carriaging can only be done with a non-erect penis. It is more of a fun play time then strict sexy time.
It feels so good Carriaging on the train, kind of tickely.
I just like to Carriage while standing in my livingroom.
"What are you doing?" "I'm Carriaging, try it"
"Carriaging, you are sick" "Dont knock it till you try it"
"Damn, Carriaging is good"
I carriaged the shit out of her face, she loved it but then I got hard so I had to stop Carriaging.