Everyone loves a delicious bit of irony from time to time. When we stumble upon these unexpected moments, they get easily stuck in our heads—after all, we know irony when we see it. But when it comes to defining the term and expressing it with words, many people have difficulties.

The most basic definition of this term is a conflict between what’s expected and what occurs. To learn more about irony and its humorous nature, we reached out to Roger J. Kreuz, Ph.D., a professor of psychology and an associate dean of the College of Arts and Sciences at the University of Memphis.

In his recent book, Irony and Sarcasm, Kreuz goes into great detail in explaining how and why these words “are two of the most misused, misapplied, and misunderstood words in our conversational lexicon.”

While many of us instinctively understand when a situation is ironic, it can be hard to articulate it. The professor said that the reason behind this is that “the perception of irony is triggered by violations of implicit assumptions that we have about the world and how it is supposed to work.” 

“In most cases, we aren’t even aware of these assumptions until we encounter something incongruous or peculiar that contradicts our expectations,” he added. Kreuz provided a couple of examples: 

• You encounter a sign with a misspelling in front of a store. Not a big deal – mistakes happen. Not irony.
• You see a sign in front of a school. Many schools have such signs, so nothing surprising about that. Not irony.
• You see a sign in front of a school that reads “We are committed to excellense.” Educators are supposed to know how to spell, so the juxtaposition of the message, the mistake, and its very public location triggers a sense of irony.

“In a similar way, a destroyed book is not ironic, and a book about dog training isn’t either,” the professor continued. But if you juxtapose them and see Dog Training for Dummies being destroyed by your furry four-legged friend: “Voilà, irony!”

One thing that many people tend to mix up is verbal irony and sarcasm. These two words often are used interchangeably, yet they’re not the same. “Irony is often triggered by situations and involves incongruity, juxtaposition, and unexpectedness. Sarcasm, on the other hand, is typically verbal,” Kreuz told Bored Panda. 

“It often makes use of irony to criticize someone else, or to be humorous. But not all sarcasm involves irony, which is why people are often confused about these terms.”

And talking about why many of us find it comical when we come across an ironic sign, poster, or image, Kreuz mentioned that we think it’s amusing because it’s almost like solving a puzzle. “When we spot the incongruity, we can be amused, and then perhaps consider ourselves to be a little superior compared to those who don’t ’get the joke.’”

Looking through this list, you can’t help but feel reminded to expect the unexpected and chuckle at the ups and downs of life. After all, ironic billboards, posters, and situations are lurking all around us, just waiting to be captured and shared with people in great need of a laugh or two.