I like to ride my unicycle. It has only one wheel that touches the ground. 
You must be talented to do that
I do ok, but it can be practiced professionally at festivals or by street performers. 
Is it a circus event too?
Yes it can be done at circuses! Some people even ride it on mountain biking trails. 
OK ,when sis it originate?
It's hard to say but patents first appeared in 1869.