I can not imagine a more different set of pictures. It was pretty hard to come up with a theme that could work with all 3.
The tongue was the stumbling block for me. I knew I had to include it today, but the only good thing I could think of was having the weird tongue represent being internally different.
It's not that the images have to be exact photographs of what is in the text, but they do have to represent the feeling of the caption beneath them. The person in this one is not a dog like frame 1, but the dog in weird clothes does represent people being forced by society to look one way. (The dog is cute too!!)
Frame 1 and 2 used to be the other way around, but looking at yahoo again I noticed that the sequence had changed and that the whole thing would work better in that order.
Oh and I am not at all sure that the punchline is actually funny and that it is enough of a non-sequitur.