Back in the same era, an enterprising young hacker of my acquaintance obtained unmetered access to another of those pay-by-the-hour dialup services by messing with window Z-order. The dialup service's GUI client had a free tech support area; billing stopped once you opened its window, and did not start again until you closed it. The rest of the system was all still there and running as usual - you just couldn't click on any of it while the support-area window was active.

So... this kid whipped up a little bit of code which let you force the topmost window to the back, and proceeded to spend impressive quantities of time online doing apparently nothing in the online service's free support area.