Pure exhibitionism.  

I've done solo cam in the past, and it can be a real ego-booster for a little while.  But maybe that's just me.

I'm just the opposite, but I'm glad that there are some who are.  It makes life a bit interesting.

That's what my pastor said anyway.  
Well, former pastor actually.  
He's in prison right now for embezzlement.

I have no desire to let anyone whip me or hit me with objects or shove said objects up my rear, but hey some dudes dig that stuff.  Some folks like voyeurism.  We had this lady when I was in college who would always sit in her car with a short skirt on, no underwear and prop her leg on the dash.  She was in her 30's and really liked 19yr old guys checkin out her pussy.  All kinds of guys asked her out, but as far as I know she never took up the offer she just liked to be looked at.  Naked women in my bed tend to motivate me quite a bit.