They should really branch out into proper porn spinoffs considering how masterfully they mix story and titillation. The production value would be immense.

Game of Boners - Aiden Gillen returns to his brothel to make use of his Littlefinger namesake.

The Sopranals: Gandolfini enters Bada Bing! through the back door

etc. etc.

Which is to say, HBO actually seem to be quite tasteful with this while also being gratuitous.