…or, more precisely, the humourists who tried to explain Einstein’s theory of relativity were wrong.
This is what you commonly hear:
When you sit next to a pretty girl for one hour, and it feels like a minute. As opposed to when you sit on a hot stove for one minute, and it feels like an hour. That is relativity.
That’s got nothing to do with the concept of relativity of time as defined by physics. But it’s an example used to explain that time is not constant. The example is used because it turns out that events in our lives do have an effect on our perception of time.
And still that example is not quite that good because it turns out that time with a pretty girl can actually feel like one hour if what you feel is novel enough. Joshua Foer explains:
Monotony collapses time; novelty unfolds it. You can exercise daily and eat healthily and live a long life, while experiencing a short one. If you spend your life sitting in a cubicle and passing papers, one day is bound to blend unmemorably into the next—and disappear. That’s why it’s important to change routines regularly, and take vacations to exotic locales, and have as many new experiences as possible that can serve to anchor our memories. Creating new memories stretches out psychological time, and lengthens our perception of our lives.
An experiment where a subject spent two months in an underground cave without access to a clock, calender, or sun helped scientists come to this conclusion. Inside the cave the subject lost perception of time because of his monotonous existence. When he was removed from the cave two months after, according to his self-kept diary he had been inside only for a month.
From Joshua Foer’s Moonwalking with Einstein