Handglider

A little known phrase which can be slipped into common parlance without the other party necessarily knowing it to be offensive. The pastime of "Hang Gliding" is well known, the term "Hand Gliding" albeit sounding similar is a term associated with "Masturbation". "Hand Gliding" refers to your hand moving up and down the associated gentleman sausage.

Person 1

"Jesus Christ I have been wanking myself stupid over these last couple of days, I have nearly torn my own cock off"...

Person 2

"For sure, you are turning into a real handglider my friend"