This is a perfect example of how not to use exaggeration in a comic strip, mostly because the exaggeration is not actually part of the joke, but instead just a means to ensure the reader can understand the joke. So the use of exaggeration here is basically just a symptom of laziness.
It also doesn't help that the joke makes no sense, even beyond the annoying hyperbole of a vibrating cell phone apparently being the equivalent of an earthquake in your pocket. Why, for example, are all the soldiers receiving calls at exactly the same time? Wouldn't the joke have worked just as well with just one soldier receiving a call? Considering that all the soldiers are convulsing violently, is it really necessary for Corporal Yo to ask how Sarge is aware of the cell phones? And considering that a vibrating cell phone apparently produces seizing in the world of Camp Swampy, wouldn't the soldiers have known they couldn't hide their cell phones merely by turning them to vibrate?
Now that I've gone through all that, I'm actually beginning to wonder just what exactly the joke in this panel is. I'm pretty sure the joke is supposed to be that Sarge knows the soldiers have their phones because the phones are vibrating. But that's not even remotely funny. I don't think it even qualifies as a joke, really. The author of this strip, let's call him Mort Walker Inc., must have realized this and, in a desperate attempt to make the strip funny somehow, resorted to the poorly thought out exaggeration. All of which suggests that this strip doesn't so much have a joke or a punchline or even so much as a point. It just has a premise. Which is apparently that these youngsters nowadays carry their cell phones everywhere. Which just reveals how incredibly lame and out of touch Beetle Bailey really is.
So well played, Mort Walker Inc. Well played.