I would comment on them, but they are much too small, hardly big enough for two words, and that's not enough. There are of course a number of other things that could be said about these stickers. For example, I think they are delicious, but that is strictly a matter of taste. It is my understanding that they are not designed for that purpose, but if it suits you, you may use them in this fashion. It turns out that pears and watermelons are fairly easy to tell one from the other.
Pears are sort of pear-shaped, and watermelons are the size of watermelons.
By the way, just for your future reference, rutabagas and kumquats are generally regarded as funnier than watermelons and D'anjou pears. In fact, a cantaloupe is funnier than a watermelon, but a D'anjou pear, because it has a French name, is slightly more humorous than a Bartlett and slightly less than a Bosc. It is, I believe, important to know which are the funny fruits and vegetable. This information, by the way, is not included on the little sticker, at least not obviously. I would like to see the fruit and vegetable companies become Y2K compliant.