We know to protect our personal identification and lock our doors at night, and we're learning from the director of the FBI to put a piece of tape over our webcams to protect our privacy. But the last thing we'd expect are nasty tricks from our friendly lenders, bankers and credit card companies.

PAYDAY LOANS. You're broke, and payday is two weeks away. You request to borrow $100 from a payday loan company. It makes you hand over a personal check for $115 and sign a contract with all kinds of fine print, and it agrees to hold the check until your next payday. In two weeks it either deposits the check or hands it back to you with "VOID" stamped on it if you pay $115 in cash. But you're as broke after those two weeks as you were before. For just $15 cash more, the loan shark says, you can extend the loan for another two weeks. In other words, the cost of the initial loan is a $15 finance charge — or 391 percent APR! Then you have to pay another $15 to start over. Soon, you owe more than you borrowed in the first place. Payday loan companies are in the business of bleeding people for as much money as possible. Now that's freaky.

FURNITURE RENTAL. It sounds like a great idea to rent stuff when you can't afford to buy it. But don't be so sure. Let's say you go to the local rent-to-own store. They say: "No problem. You can rent a 27-inch television for only 78 weekly payments of $9.99, and then you'll own it." It sounds great, but don't believe it. Renting to own is a creepy way to throw your money away. In 78 weeks you will have coughed up $779 for a television that retails in other stores for, say, $217. That translates to an annual percentage rate of 230 percent. If that doesn't give you goose bumps, nothing will!

COURTESY OVERDRAFT. Banks across the country have adopted a frightening new type of overdraft plan with huge fees. Here's the scary part: You may not even know you have it. Known as "courtesy overdraft," this is different from overdraft protection tied to your savings account or line of credit. This "courtesy" service uses the bank's money to cover the checks you write over your balance. And the fees can be bloody outrageous. They don't even ask you whether you want it as incidents arise; enrollment is automatic if you made a blanket agreement when you opened the account. In addition to the bounce fee of $25 to $40 per overdraft, some banks tack on a daily fee of $2 to $5 until the checks are made good. Consumers must pay the money back within two to four weeks or risk facing severe collection actions. You do not want this service, so if they will not remove it, it may be time to look for a new bank.

CREDIT CARDS. Just how chilling are some of today's credit card offers? My all-time pick has to be the Visa card offer from Plains Commerce Bank. You pay $79 to apply for the card. Once approved, you'll have to shell out an acceptance fee of $225, an annual fee of $50 and a monthly participation fee of $6, for a total of $281. And it gets scarier.

When you add up all the fees, you've paid $360 for a credit line of less than $20, even though you've never used the horrid thing. If that's not enough to send chills up and down your spine, wait until you lock eyes with the interest rate: 19.92 percent APR! It's hard to imagine a more scary credit card.

And so we come to the end of story time. But make no mistake. This is not make-believe. All kinds of tricks like these are just waiting to be played on you. Consumers, beware!

Mary invites questions, comments and tips at mary@everydaycheapskate.com, or c/o Everyday Cheapskate, 12340 Seal Beach Blvd., Suite B-416, Seal Beach, CA 90740. This column will answer questions of general interest, but letters cannot be answered individually. Mary Hunt is the founder of www.DebtProofLiving.com, a personal finance member website and the author of "Debt-Proof Living," released in 2014. To find out more about Mary and read her past columns, please visit the Creators Syndicate webpage at www.creators.com.