Hmm, I don't really have a worst or best dream because I have a lot of crazy, vivid ones that I usually forget within a week. But, I still clearly remember the first dream I can remember, and it was a nightmare. I was 5 or 6 when I had it.
In the dream, I was in a city of some sort, with tall buildings everywhere. It was nighttime and dark. There was a helicopter with the back doors of it open, so I crawled up into the storage space that was right behind the front seats (the inside of it resembled the inside of a van) and hid in the many bags of fertilizer. There were two clowns in the front and the taller one flew the helicopter up as high as the buildings. Then somehow, they discovered me and the shorter one tossed me out of the window. I remember falling for a long time and then hitting the wet ground, but not breaking any bones or being severely hurt. For some reason there was a super tall ladder leaning against a building, so while the helicopter was hovering I propped up the ladder against the back and climbed back up & into it. The clowns discovered me again but this time, they decided to "make use of me". They grabbed me and flew up close to the side of the building and threw me through an open window. Inside, there were paintings and sculptures all over the place; it was a museum. They yelled in hushed, but harsh, tones and wanted me to steal a particular painting. I started crying, and woke up crying.
It was weird, because I was never afraid of clowns. When I woke up I ran to my mom and dad's bedroom and was sobbing about how they wanted me to steal and stealing was wrong, and how they rejected me and threw me away, but not about the clowns themselves.