A dick trick.
The man's (or she-man's) penis is wrapped underneath the ball sack till the penis is pulled perpendicular to the body. This is the "boat." Note, the balls remain behind the dick. Then, the scrotum is then stretched into a triangle where base is held against the penis. Note, the top requires pinching the scrotum and pulling up hard, which can be enjoyable or painful. This is the sail. When completed, the penis sailboat appears to be cruising at about 3 knots across the pubis. It's very popular and appropriate for most parties.
Hey, this party needs a kick, should I bust out a sailboat?
Cody's balls are so big his sailboat would be hella' fast.
I was surprised how much she liked my sailboat trick, then she let me dock my boat in her lady bay.