h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

...sleeping pets, obstructions at the level of the shin bone... Yeeeowtch! ...on that last one the answer is to be constantly mindful of the possible hazard and move slowly enough that if one does encounter a hazard at shin bone level, one makes no sound and suffers no injury.

I often think that this may be the reason for the correlation of crime rates reported by many police agencies with the phases of the moon. On a moonless night people bark their shin on the kid's tricycle, or something like that, headed down the drive and give it up for a bad job. On nights of a full moon they can see the hazard coming.