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After you get visted by Naomi you will get an option to pick the dom or sub path. If you chose the sub path and finished the game, you will need to start a new save and play through again and pick the dom path. After that just keep playing the game and at some point after a decent amount of waiting in your room for a client, Naomi will come back and "train" you a couple of times. 

I'm fairly sure that laughing or worshiping the man's balls doesn't matter towards progress on the dominant path but I could be wrong. Plus the dominant thing to do in that situation would be to laugh, so choose that one to make it more interesting.