Happens all the time on eBay. Do a search for “unicycl*” and you’ll usually get at least one item where the seller is describing a penny farthing (usually in a trinket, not the real thing), which clearly has two wheels, as a unicycle. Duh.
Just this last weekend an over ambitious and mathematically challenged
teenager [Aren’t they all? ] pointed at the 5 foot giraffe and
asked
“Can I have a go on your tricycle?”