I survive from one day to the next through the use of various home-made "guidelines for life". These are great tools.
Let's take entertainment decisions as an example, where I use the price of cinema admission as a measuring stick. An average film is around 2 hours long, and costs approximately $15. If I am considering buying a video game that costs $60, I ask: will this game be as fun as four movies? If yes, purchase. Or take a 3-day music festival. In that time, I could probably watch around twenty films at $300 (let's call it $350, as I will want snacks, and possibly special 3D goggles). If the festival is near or below that price, it is positively a steal. Purchase.
In the same vein, I make up my mind about how I feel about new inventions or ideas with a simple question:
"Would the Ancient Romans be impressed?"
Things like powered flight and mobile telephony are obvious no-brainers. These would knock the Romans' socks (or sandals) off. There is no way Hannibal would have snuck several zoos worth of elephants into Italy if the Roman General Scipio had roaming 3G coverage from which he could receive picture messages from his scouts.
But other modern things would not have impressed our Latin ancestors in the slightest. I give you two examples.
Snuggies. The proud, toga-wearing Romans would have been positively furious at these. Unlike the versatile toga, the Snuggie keeps you at only one temperature: sweltering. Furthermore, the Roman toga was a badge of both style and class—the garment was usually made from the finest wool, and was only allowed to be worn by Roman citizens. These days, any lazy slob can order a mass-produced Snuggie from the comfort of their couch. Seeing their beloved garment in the hands of the unwashed masses would give Romans of old a caezure.
Goths. In the year 410, the Visigoths sacked Rome, the first time anyone had ever done so in 800 years. While Romans may not have taken a shine to these goths, they at least would admit that they were an impressive, winged-hat wearing bunch of warriors. The Ostrogoths popped around later in the century to finish the deed by establishing their own kingdom upon the ruins of the Western Roman empire, led by King Theodoric, a savvy politician.
In contrast, the unwilling king of the modern-day goths, Robert Smith, holds sway over a disaffected band of ne'r-do-wells that pale in comparison to their ancient namesakes. During the Visigoth sack of Rome, the shocked population of the city fled into the countryside as Roman institutions and landmarks were desecrated, and the city's wealth lost. If only Rome were so fortunate to have been sacked by modern-day goths! In such a scenario, the only territory lost would have been the steps of the Pantheon, where the goths would sit for most of the day to avoid the sun and discuss their "worries".
Most importantly, King Smith (a fine musician) loves cats, whereas I have it on good authority that the Romans, if forced to choose, were ultimately dog people.
The above is just a taster. What else might draw the ire of the Romans?