Sometimes you have to use your imagination, and a little technology, to accomplish a prompt.  I'll admit that I had a hard time finding a subject that I liked for a long exposure photo.  In the end, I turned to Photoshop to create my "dancing tulip" effect.  And I learned something new in the process, a process that is very simple!  Choose a photo with a clear subject. 

• Open your photo in PS.  Crop if necessary. Duplicate the layer.
• Go to FILTER-BLUR-RADIAL & Select Spin and Best.  Hit OK.
• Add a mask.  Select the brush tool with Flow set to 50%.  Erase some of the blur to reveal the details of your subject.
• Go to bottom layer (original photo) and duplicate it again.
• Go to FILTER-BLUR-MOTION & Set angle to your choice and Custom to 200.  Hit OK.
• Again, add a mask and with the brush tool and same settings as above, reveal desired detail in your subject.
• Continue the editing processing as you would any other photo.

Use your imagination and have some fun!