I had this friend once, sort of the "burnout" type, who I had to cut out of my life. All through highschool we were close, but after highschool he didn't really do much with his life and I went off to college. We would still kick it over the summer or on random weekends when I visited home, but his life just kept going downhill. Always in trouble, steady but shitty job, no motivation to do anything but get lifted all day. Anyways, one summer he got in trouble for stealing a bottle of liquor from Walmart. He called me from jail and asked me to come bail him out. I truly felt sorry for him, and against the advice of my parents and friends, I paid the 150 to bail him out. He didn't have the money, which was cool with me. I wasn't hounding him about it and I never did. Flash forward to fall semester of college a couple months later, I get a call from my friend. He has lung cancer, he tells me. He doesn't know what to do and hasn't told anybody but me. He tells me,how sorry he is that he hasn't paid me back and that its because he's been paying for his treatment. I understand completely. I cry on the phone with him for awhile, before telling him that he has to tell his parents. He says no, they can't know, you can't tell them they'll be scared. Ok, whatever, I thought nothing of it. Anyways I try to talk to him as much as possible, see how he's doing, keep up to date on his situation, give him encouraging words, and we become close again. Then one day when visiting home for the weekend, we hang out and he tells me he's cured. I'm amazed. He says he stopped breathing in the middle of the night and the took him to the hospital to do an emergency surgery. They pulled the tumor in his lung out through a tube that was placed down his throat. I wasn't familiar with tumor removal surgery so I thought nothing of it. But when I get home all excited that my friend is cured of cancer and tell my parents the story, the explain to me how gullible I am. There is no such tumor removal process as my friend described it. He never had fucking cancer. He just didn't want to pay me that measly 150 bucks. I cried for this piece of shit, afraid that one of my best friends could die. After realizing what an idiot I had been, I cut off all contact completely. He still tries to talk to me all the time. And although I do miss the friend I used to have, I just can't have people in my life that I don't trust.

TL;DR: My friend didn't have the money to pay me back for bailing him out of jail, so he fakes having lung cancer to get out of it.