After college, all my friends went to Silicon Valley to get a job. I got delayed 1 month due to health issues. This was exactly 2 years from today. (August 13 to be exact). My college friend, whom I had known for 4 years, asked me to come stay with him. As he was staying with his elder brother, he suggested that after I move to the city, we shall rent our own place. I thought "Alright, I trust this guy, we have been good friends for 4 years, so we can be good roommates." Worst mistake of my life.
When I arrived to the city, He called me at his current residence with his brother, and I stayed there for 3 days while searching for an apartment. Once we agreed on an apartment, he asked me to pay for the advance (40% of rent), and said he would pay me back afterwards. The very next day I moved in with him to the new place. One day later, he sends his friends to get his luggage out, and called me saying that he is gonna move in with them as he knows them from his school time and some other crap. I was shocked by such behaviour, I didn't know how to react. I mean I can't stop his friends from taking his luggage, because I got no right to do so. Meanwhile I was left alone in that apartment by myself and had to pay full rent if I didn't find another roomate soon. Soon after, the landlord came in asking for the entire month rent for two people.
Fortunately, I didn't sign any contract with the landlord, although he tried to strongarm me to do so, even giving me threats of reporting me to the police. I politely told him that I haven't lived there even for 24 hours and already paid an advance, so reporting to police will not be fruitful. He told me to either pay the entire rent straight forward or vacate the apartment. I opted for the latter. Although I lost my money, I was relieved that the landlord let me go without much problem and even offered lunch before escorting me out. I then moved to a hotel, after which I returned home. It took me about 1 month to get the courage to return back to the city, but this event taught me one very good lesson, 'Trust only yourself'. The next time I went, I lived by myself, got 2 jobs before him, and enjoyed my time in the city to the fullest.
TL;DR: Friend asked me to be his roommate. Bailed out after 1 day. I lost security deposit and ability to trust. Still happy because now I am completely independent and can judge people better.