The first sign comes from the Netherlands where it's very common. The reasons for this choice are easy to understand, but better products are on the market even for people who prefer ugly roadside ornaments (see below).

The second find is a modern version of sign we've seen in Washington: an atletic boy makes it clear that the SLOW is a command and not meant as a description.

The drawing confirms my observation from Canada: modern roadsigns show no clothing (unless he's wearing a spandex suit; but then he must be the proverbial exception).