When a Sim has been afflicted by the mummy's curse for about a week, the screen becomes surrounded by a strange sort of glow whenever said Sim is selected. Let another week pass, and the edges of your screen will dim to black every few seconds. Your Sim's vision blurring and clouding over as they slowly die, perhaps?
If a Sim dies before they turn their imaginary friend real, the imaginary friend doesn't die with them. They remain wandering around the lot, and then fade out once you select another Sim to control. Just like they did before their Sim died. Does that mean that imaginary friends can't ever die? Do they wander around endlessly among the grieving family members, unable to communicate without their Sim to talk to?Forever?
In Late Night/Supernatural: to keep Sims T Rated, vampires will drink plasma, the Sim equivalent of blood. While this isn't too bad on its own, notice that plasma is available in the quick meal section of the fridge. Did we mention you never run out of quick meals? So essentially, your Sims keep an infinite supply of Sim blood in their fridges at all times.
Cheaply produced plasma fruit juice, not exactly the most tasty thing on the Sims menu but serves it's purpose. Just don't drink it if you are a regular Sim without an enhanced immune system.
Most of the fanbase considers the plasma juice Sims get from the fridge to be the Sim equivalent of TruBlood, whereas the plasma vampires get from sims is real blood.
The ghosts of Sims that have died from hunger have little speech bubbles about it the same way alive Sims do. Does that mean they're always as hungry as they were when they died?
Fairies can fix things by turning into their miniature form and repairing them from inside. That includes unclogging toilets.
Probably the most egregious example is that you can have an entire town of mayors. You can even have an entire town's worth of presidents.
There exists a mod for The Sims 2 that limits the number of sims in many higher job levels per neighbourhood for exactly this reason.
A more common example is that, while Sims need a phone to receive phone calls (which is perfectly good logic), they don't need a computer to receive and send back e-mails. There aren't even enough public computers to make it plausible that the computer-less Sim is just checking their email on public computers.
Unless you build more places with public computers, of course.
Maybe they are using their cell phones, perhaps?
In The Sims 3: Into the Future, your Sim can travel to the future and meet a family made up of their descendants. Which means that both husband and wife are directly descended from you. Which means - oh god, ew.
The Sims 1 (as a very basic form of human life simulator) is based upon Maslow's Hierarchy of Needs; Sims are happy as long as they are fed, rested, kept amused etc. The Sims 2 retains that but with the added depth (and human realism) of Schopenhauer's theory of the "Will" – interchangeable here with the added “Wants” system in the game. Indeed, the “Wants” aspect is true to Schopenhauer’s view (almost scarily so) in that TS2 Sims are constantly hungering for more and more (success, popularity, material possessions, sex and so-on). In addition, even when they get what they want their fulfillment is relatively short-lived (the “Aspiration Meter” level depletes) or, conversely, boredom ensues – though probably more for the player than for them. The only [unrealistic] digression from all this is the introduction of the “lifelong aspiration” in a later TS2 expansion which, if accomplished, would grant the sim platinum aspiration level for the rest of their life.