People have asked to buy pot off me a twice in harvard square, though I think they were joking (pretty sure they were homeless people). I've had pot and coke offered to me, but to purchase, multiple times, especially pot. I get asked if I want pot in harvard square all the time, and in chinatown as well, though chinatown is the only place where I ever get offered hard stuff. Had a food prostitues try to sell themselves to me as well.
Also, a bit unrelated, I was walking in downtown toronto when this guy came up and started talking to me. Basically, the guy wanted to have sex, he gave me his number and I said I'd call him. I had no intention of doing so, but it made my day so I was essentially prolonging the moment.
edit:
Just remembered a pot story that happened to me. Me and a friend were had just finished playing basketball and he walked back to my car, I was picking up some stuff and then went to my car. He was talking to some kid and my friend asked me if I would drive him to his house, I said ya. When we get in the car he starts telling me how he stole some pot off a kid who was selling it, the reasoning was this kid had tried to rape his sister. My friend said something that caught me as odd and I said and, after a few questions, I realized that this kid was my friends friend, but just some kid his ran into in the parking lot. I was ready to kill him. Then this kid pulls out some pot offering it to me as thanks for giving him a ride. I say no and proceed to get him home and out of my car asap, the kid was offering to pay me (which my friend kept telling me to accept), but he had to go in his house to get it and I didn't want to stick around any longer than I had to. My friend, afterward, kept saying he couldn't believe I said ok to drive him, but anyone would have though that this kid was his friend and not just some stranger, especially since my friend asked me to drive him.
Also, my car really smelled like pot even though it was only open for a minute (must have been good pot to be so strong), I spent about 4 hours at my friends house (from about 10p.m.- 2a.m.) and left my car outside with all the windows down to get rid of the smell so my parents wouldn't kill me.