MINNEAPOLIS (WCCO) — On Thursday, you may have seen or heard the term “catfishing” in the wake of Deadspin’s story on Manti Te’o's nonexistent girlfriend.

Many people have online relationships, and there are times when someone misrepresents him or herself.

But what is catfishing? And how could someone be so gullible to fall for it?

When one in five relationships starts online, some of them are going to go wrong.

Nev Schulman, 24, was in a documentary called “Catfish.” He lived in New York and met a girl online calling herself Megan.

He drove to her Michigan farm and found young Megan was actually a housewife named Angela. The movie spawned an MTV show, also called “Catfish,” which focuses on online relationships that turn out to be a frauds.

“Some people are [catfishing] because they want revenge, they have an ax to grind,” said Laurie Davis, the author of an online dating guide book called “Love at First Click.”

She said catfishers will usually dodge dates.

“There will always be an amazing reason for the date dodge that makes you feel like it’s nothing you can complain about,” she said.

But how could anyone fall for it?

“There’s a loneliness inside of you. With that loneliness you want to see good in people,” said Kimberly Koehler, a dating coach who runs online dating bootcamps.

So how should you approach online dating?

“You want to be cautious. You want to be optimistically cautious,” she said.

In some cases, the catfisher ends up stealing money. But there’s always loss once the fraud is revealed.

“Just as much as the loss of money is the pain of the heart, because these people are really falling in love,” Koehler said.

Both of dating experts stressed the importance of meeting in real life. Davis said no more than six messages before meeting. Koehler said three emails, then go to phone, then insist on meeting.