Picture this: your 90-year old grandmother gets a phone call, which goes like this:
"Hi grandma, it's me!"
She tries to recognize the voice and says:
"… Paul?"
"Of course! I have a big problem, grandma."
"What's wrong, sweetie?"
"I got in a bit of trouble, but please don't tell mom."
The “grandson” then informs the elder that a series of unfortunate events has gotten him in jail. He needs bail money. Grandma might be skeptical, since the caller might not sound exactly like you, but the scammer knows that. That's why right away he passes the phone over to his “attorney” who gives grandma details about the charges and information on how to wire the money.

How to avoid: let your parents and grandparents know about this scam. Basically, if anyone ever calls asking for money, talk to your family and confirm that they are where they say they are. It may seem common sense, but the emotions usually overtake the seniors.