They’re feeding you a lie.

Nearly one in five millennials (17%) and Gen Zers (19%) say they’ve chosen a hotel room or leisure trip destination so they could get a positive response on social media, according to a study released Wednesday by Expedia. “We’ve found that Gen Z and millennials care a lot about public perception, likely because they grew up in the age of social media,” explains Expedia’s VP of Global Communications, Sarah Gavin.

And they care that things appear more luxe than they actually are: More than half (56%) of millennials say they’ve posted a photo on social media to make it look like they were staying, eating or visiting somewhere more expensive than they actually were, according to a survey of 1,000 people released in 2017 by financial site LearnVest.

One reason they do this is because they’re trying to “create jealousy and make themselves appear more desirable,” especially to a former or current love interest, says Fran Walfish, a Beverly Hills family and relationship psychotherapist and author, and the co-star of “Sex Box” on WE TV. Many also have materialistic values, she adds. Indeed, a 2012 study published in the Journal of Personality and Social Psychology noted that millennials are “focusing more on money, image and fame” than previous generations.

Also see: If you have sex with a rich millennial, expect this power dynamic.

Whatever the reasons, one thing is clear — those kinds of posts are likely to have a negative effect on their social media friends and connections. Most millennials say they feel pressure to keep up with their friend’s spending — and of those, nearly half say that social media posts of friend’s vacations and lifestyles contribute to that pressure, according to data from TD Ameritrade. And a separate survey found that more than one in 10 people admit to buying something like a vacation because they saw it on their friend’s social media.

That may explain why millennials are way more likely than other age groups to go into the red for a vacation: Nearly half (49%) say they would take on debt for a good vaca, compared to just 37% of Gen Xers and 18% of boomers, the LearnVest survey found. That’s a costly move: If you slap $1,000 on your credit card at a 15% interest rate, and just pay the minimum (assuming that’s 4%), it’ll take you about 65 months to repay that debt and cost you more than $1,300 in total.