This is the most underused piece of a mans wardrobe. The top button on a button down. When this is buttoned, the man is at his highest level of status, thus he has reached the penthouse button.
Maxing and relaxing in a penthouse, generally involving alcohol, drugs etc... but especially bad bitches. It is also a state of mind where the world is your oyster and you are looking down upon it, not just thinking you are better than the plebs below you, but knowing it.
OG "Broo what did you mean by penthousing last night?"