Wet cement
Oh, look! Wet cement! Let’s get on our hands and knees and watch patiently as it dries! For obvious reasons, nobody does this. Sadly, what some people do is step all over barely-dried cement, leaving shoe and foot tracks all over the top surface. Why would someone do such a thing?

Don’t even bother asking. Common sense isn’t as common as think. Ruining the cement walkway serves no purpose to anyone. We’d much rather have someone press their face into wet cement and write their names with a finger. At least it’d be easier to hunt them down or report them to the police.