Co-signing on a credit card or loan can be a hand up, but vouching for the wrong person can turn into a costly handout.

The folks at CreditCards.com recently surveyed more than 2,000 U.S. adults and found that one in six have co-signed a loan or credit card for another person. However, 38% of those co-signers had to pay some or all of the balance after the applicant/borrower fell short. Worse, 28% watched their credit scores drop because of late payments.

Unfortunately, 26% say co-signing damaged their relationship with the person they were trying to help out.

"With a 38% chance of losing money and a 26% chance of damaging a relationship, co-signing doesn't sound like a very good bet," according to Matt Schulz, CreditCards.com's senior industry analyst. "If you absolutely have to co-sign, then at least be aware there's a sizable chance you'll lose some money and/or get your feelings hurt."

So who's getting burned on all of this co-signing? Look no further than the Not-Quite-Greatest Generation: Baby Boomers. Nearly a quarter of 50- to 64-year-olds have co-signed a loan or card for someone else, compared to 22% of those older than 65 and 14% of those ages 30 to 49. Of those earning more than $75,000 a year, 24% have co-signed on a loan, compared to just 11% of those earning $30,000 or less.

Why are they putting their own money and credit on the line? Because they're infatuated with their kids. Roughly 45% have co-signed for a child or stepchild, compared to just 21% who co-sign for friends. With their Millennial children buried under college debt and just now finding stable employment, Boomer parents are signing for auto loans (51%), personal loans (24%), student loans (19%) and credit cards (16%).

"Boomers and Millennials are as much friends as they are parents and children," says Paula Polito, client strategy officer of UBS Wealth Management Americas. "Their unique relationship deepens their bond, and they maintain both close emotional and financial ties."

That hyperbole is backed up with a whole lot of unconditional money, as a UBS survey found that nearly three-quarters (74%) of Millennials receive some form of financial assistance from their parents. A majority (80%) of Boomer parents says they feel good about propping up their kids financially, while only 10% would withhold money to teach adult children financial responsibility. Though 52% of Millennials feel shame, frustration or guilt about accepting help from their parents, they still take it for: health insurance (29%), home buying/renting (28%), auto insurance (26%), utilities (23%), vacations (19%) and spending money (21%).

This is on top of allowing their kids to live at home, which 22% of Boomber parents want and which 24% of Millennials prefer. As a result, financial firm The Principal found that despite 84% of Millennials saying that people should be financially independent by age 25 or younger. Millennials still rely on parental support for cell phone bills (12%), car insurance (8%), health insurance (7%) and rent/mortgage (7%).

As Boomer parents know, a good credit score can be a valuable asset for someone with bad credit trying to get a loan or credit card. Having a co-signer back that high-risk borrower may help lenders view an application more favorably, which is particularly helpful for young applicants who have little to nothing on their credit reports.

That said, if that young person has been a financial mess before asking for a co-signer's help, their bad financial habits won't automatically disappear once a parent co-signs for them. Also, if a parent doesn't have the resources to pay the loan they're co-signing for, they should be incredibly wary. CreditCards.com found that 58% of those who make less than $30,000 annually were stuck with some or all of a loan or card bill after co-signing. It's the reason why only 17% of adults reported co-signing on a loan or credit card. Some experts believe it's because most people are already wary of the dangers of co-signing.

"Once you co-sign, you are legally responsible for the debt," Michelle Dosher, consumer engagement program manager for the Credit Union National Association, told CreditCards.com. "It can be hard on you and it can be hard on family and friends if that situation doesn't work out as it was intended."

This article is commentary by an independent contributor. At the time of publication, the author held no positions in the stocks mentioned.