The bumper sticker read: Be kind to animals, don't eat them. Asides from the huge moral heteronomy that this message is presupposing, there is a strong inconsistency within the course of action that it proposes.
Let's suppose that not eating animals is kind for animals. There are two options, either we eat something else, or we die. The second option has the consequence that, if you want to be kind to animals, you should starve. The other option, however, has a more problematic consequence. Given the facts of how the environment is, if we eat something else but animals we end up killing them (not that kind), or starving. Thus, whatever we do, if we don't eat animals we'll end up doing something not kind to them, or to ourselves.
Here's why. If you eat something else, say, soy, then you'll end up modifying the environment and destroying the food resources for those animals you intend to be so kind to. If you don't believe me, take a look at this.
So let me see how the argument is supposed to go. Be kind to animals. Eat soy. If you eat soy you help increasing deforestation (e.g. Brazilian Amazon). However, if you help increasing deforestation then you help destroying the animal's environment and, with it, its food resources. Thus, the argument goes, “Be kind to animals, destroy their environment and eliminate their food resources.” What a way to be kind to animals!!
There's also the chance, I must admit, that being kind to animals implies not eating them, or anything that affects their environment. But then, unless Ecology is mistaken and it is not true that the world as a whole is an environment intricately connecting every single part with the rest as part of an alimentary/consumption chain, there is nothing left for humans to eat. Thus, the claim goes: Be kind to animals, starve!
This is what happens when you get to stupid arguments such as not eating animals in order to be kind. You get something like the following.
Be kind to animals. Destroy their food resources. (inconsistent)
Be kind to animals. Starve. (nonsensical)
Unless we find a way to step out of the alimentary chain without dying in the process (oxymoron?), be kind to yourself and eat animals.