Sure enough, before long someone asked "You got a flat tire?"
"No." I replied. "This is just an oversized pedometer fitted with a drink holder and brakes."
Some people are looking for an opportunity to be helpful when they ask if you have a flat. You never know, the person you reply sarcastically to may have a pump and tube/patch kit around the corner. Or a van in which they might offer you a ride to your own pump and tire repair stuff.