Good job to all participants — Rock Star is now closed. As to the little trick that some players alluded to earlier in the thread, here it is — there are 3 songs on the electric guitar when performed have the result of being played incredibly fast. It's almost as if they cancel out. But, the difference here is you're not intentionally exploiting and doing the canceling — the game for whatever reason is doing it for you. This is not a brand new trick — it's been around a while which is partially why I elected not to look upon this as an exploit too. EA clearly knows about it and have not fixed it, so maybe it's an "Easter Egg" kind of thing where developers throw players who snoop around a bone.
So, combined with Motive Mobile which I was able to pick up after my Rock Star achieved his LTW I could grind my guitarist 24/7 with performances. In the end I stopped at 3500.
But, with most tips in the 10-15k range how in the world did I get that big one? Well, I think it was NancyJ that brought up double tips earlier. This is where two Sims approach the guitar case at the same time and toss in their tips. The game then adds those amounts together and you get a double tip. So, that's clearly what happened. It may have even been a triple tip because it seemed to me that 2 Sims were on the side and one was directly in front. So, was that a little lucky? Yes. Do I know how to increase the chances of that happening? Yes I do. You're obviously not going to have double/triple tips if a single Sim is watching your guitarist. You need a big crowd. Weekends in front of the Theatre have always seemed best — late in the day and into the evening. Eventually it seems a lot of Sims lose interest and start talking or dancing which means they're not approaching the guitar case and tossing money. That's when it takes a trained eye to know to cancel the action and fire it up again. That halts everyone in the immediate vicinity in their tracks and puts their eyes back on the guitarist and you'll have multiple Sims approach the case.