This morning on the cargo bike my 4yo brought up the existence of "bicycles that are like a bicycle but they have only one wheel and they don't have these [makes a handlebar motion] and you have to hold your arms out to the side to balance".
So we had a nice chat about unicycles and penny farthings and the invention of the 'safety bicycle'.
"Well I want to call this bicycle a safety bicycle. I like that. I'm going to do that."