It is as it sounds: a Man (yes, capitalized for this instance as only a true Man can pull off this maneuver) unzips his pants and takes his dick in both hands and slams it down
on the table to prove his point. This is only to be used in
circumstances where without slamming the cock
on the table, the story, argument, etc. would be laughed off otherwise.
At a sales
presentation:
"...and that,
ladies and gentlemen, is why you should invest in my company."
"But it makes no sense!"
(audience grumbles and
discontent grows)
"Well maybe this will make my point better"
(presenter drops trou and performs the 2 Handed Dick Slam)
Audience applauds and the Man goes on to riches and fame.