Doereoh: the
Plumbbobtoggle [on/off] cheat requires Open for Business EP although some people report this cheat works in NL, Maxis does not list it as offcial until OfB, so you would be best served by the
No Ballons Patch at Simlogical (near bottom of page) - this is the same as mentioned by justluvly, but in its proper home with the commentary by the crator.
NO BALLOONS PATCH (base game & University EP compatible)
13th May 2005 updated to include plumbob hider
Note: Although this works with Uni, I haven't actually updated it. The EP may have some extra balloons that will show up.
I didn't manage to get rid of *all* of them. They still notice popular or romantic sims, and have desperation balloons, and new possession balloons. However, the plumbob is gone. But to get the most complete effect you really need to start with a new family and new lot after installing this patch.
There are three files - the one called "extra" has stuff in it that *might* affect gameplay and make them not earn skills etc. I don't use this patch myself so you're best off asking people who use it what if any exact effects it has. The one called PlumbobZapper is actually an object in your catalogue (under Misc/All) - it's a CD-ROM. If you find the patches are not getting rid of the plumbobs, then place this on the lot, and it checks for plumbobs every few minutes and hides them
Good for storytellers. NB: This patch will probably infect uploaded lots.
Not needed for Nightlife or later, which has a cheat code for this.