I have been riding for just over a week and have already had at least 20 people ask me “Where’s the other wheel?”. I got annoyed after the first 5 times and was wondering if any of you lot had some good way of answering. The best I have seen is:
Other wheel? 
Where the f*** did it go (and promptly fall off).
oh s***! (and fall off)
“those are for wimps!” then do a lovely series of flatland tricks
There are countless other threads on this, do a search.
‘Wheres your other wheel?’
‘I left it in your mother!’
Mike
I use this one the most. It pees some people off. But most of them have a sense of humour which is a good thing to have. 
other wheel?? I don’t need no training wheel anymore
I use this one the most. It pees some people off. But most of them have a sense of humour which is a good thing to have.
other wheel?? I don’t need no training wheel anymore
Damn overcritical little… will do in future. Your response is the best by far though.
I only posted what I said to get my joke out. I hope you got ‘it’. Sorry :o
Mike
Here’s a good one.
When you go to this website click where it says “For more answers, click here”
http://www.unicycle.au.com/View.php?action=Page&Name=General
Hoped this helped somehow
Hazmat
lol ive bin unicycling since christmas day and a couple of people have asked me that, all i said is i couldnt afford the other wheel
I tell them the bike shop had a 50% off sale, so this is what I got.
I got mine for Christmas aswell. It’s from oddball in Camden, the best shop ever. I get everything from there, diablos, kites, skateboards… Literally everything.
Keep em coming
I usually say “Blimey, it was there when I started. I thought it felt funny”.
lol, today i had a guy say this: “thats the biggest one wheel skateboard in town” i was like…umm…ok “the prefered term is unicycle”
Yeah, they’re very friendly and helpful in there. Sadly I don’t have enough excuses to go in and buy stuff 
By the way, if you’re able to get yourself down to Hackney on a wednesday evening, there’s unicycle hockey going on, and people of all abilities are welcome… You’d be amazed how quickly your riding progresses once you’re concentrating on all the other stuff going on around you!
STM
The bike is for the unimagitive person.
I am not missing a wheel… if I was, I wouldn’t have one under me!
I like this one:
Two wheels? That’s twice as hard.
When asked, “where’s your other wheel”, or whatever, a good answer it: “I like a challenge, what’s your excuse?”
The other wheel just gets in the way.
Whenever im riding with my mate, i say “its just coming” and along he comes:D
its funny as hell