"Sometimes the electricity is only switched on if you’re in your room and have inserted your card into the corresponding slot. But what if, for example, you need to charge your phone and go somewhere else? You can insert another plastic card, even a travel card, into the slot."
but i also have never been to McDonalds-Country.
Merica amirite
Depends on the country. In South America they’re usually not when you go into cheap hotels, which is also where you’d want to use this technique
All of these are basic or dumb ideas that won't work in a low budget motel, or are meaningless (towel under door is a safety hazard only illegal room smokers do).