What the hey...I may as well respond to your question.
Let's see...the sky is blue because of the sun's rays...oh, sorry.
Hmmmm...A "professional" juggler? Well, I know that I'm not one, and I don't know any professional jugglers either, so I'm probably not qualified to answer this...but that won't stop me!:) I can best realte this to my brother's favorite waste of time: skateboarding. The difference between an amateur and a professional skateboarder is that professionals get endorsements and get payed. "Professional" athletes, in general, are those who get payed to participate in their sport.
So I guess a "professional" juggler is a juggler who gets payed to juggle...Wait a second...Is that possible? Why has no one told about that? I could have quit school a long time ago to juggle for a living! Well, maybe not...oh well.
Of course, "professional" could refer to a juggler's personality, such as, "He acted in a very professional manner."...but I digress.
Banzai
banzai16@yahoo.com
P.S. Wow, that was really long for my first post here!