I decided to play the Lee house in Starlight Shores. He wants to become a DJ. His garage is set up with a booth, professional juice bar and dance floor. I am guessing he can have parties and play his DJ booth. He can place his booth in his inventory.
I noticed after his wife requested a song change a few times, a pop up told me that he learned how to work the booth.
I had him take the booth to the park during a grill a thon. He played the requests for tips. It started out with a few sims requesting music changes and giving him a tip.
I am guessing that the tips will become worth more with the more requests and levels that are gained with practice over time.
I have only been playing the Lee family a few sim days, this is just what I observed so far. I tried to have him practice with the DJ booth all Sunday long, but he did not gain any skills. The minute his wife came over and requested a diffrent genre a couple of times, he gained a skill level with a pop up message. So I think the skill is built with requests. When a stranger requests a change, he gets a tip.