Cats are filled with whimsy and quirkiness, especially when they are kittens. We have laughed ourselves to tears while watching some of the kittens we have welcomed into our family wrestle or chase blowing leaves. Cats are always batting at whatever moves and pouncing when you least expect it. So designers who create whimsical products often choose cats to exemplify everything that tickles the funny bone.
Many of these clocks show cats with their "friends" who are really some of their favorite meals -- birds, mice, even the bee that knows how to bite back (or rather, sting back). Although cats don't mean to be funny when they are on the prowl -- they think of themselves as really serious and even savage -- watching a cat unsuccessfully pursuing their prey can appear funny to the observer. (Unless, of course, they are successful, but we won't talk too much about that.)
Designers have produced some really delightful clocks with a cat theme that would be fun to collect and put on the wall. They'd be fun to give as gifts, too.