This happens EVERYTIME when I ride my uni and encounter bicyclists.
After seeing me ride my uni, the bicyclist begins riding ‘no-hands’ on their bike.
As if to say, “Hey, I can do what you’re doing on my bike!” 
Tell them if they wanna be like you so bad, take a wheel off and do the same, or buy a uni 
That’s when you put your hands on your handlebar and give them the same snarl back as if to say: “Hey, I can do what you’re doing on my uni!”
I once had a motorcyclist do a stoppie for me.
Haha, I was going to say same thing, they tend to start riding “no hands” 
that’s funny
Could you ride backwards, or seat out? Or any simple trick to challenge them? Or ask them if they care to try the uni?
When a bicyclist asks WYOW, I always say “I decided to take off the training wheel”
Haha, this happend to me yesterday! A teenager started going hands free after seeing me riding a 36er. I wasn’t even good at it, it was only my 2nd ride. ~_~
I saw a biker riding no handed today. I put my hands out on my big imaginary handlebars as I rode past.
To be fair I see a lot of bike riders riding no handed when I’m not on my unicycle too though I have noticed this tendency.