Do you ever do the talking for your pets? Say the stuff you think they should be saying? No one admits to it, because it seems really silly when you say it out loud, but just about everyone does it. Heck, my grandmother used to do it, and I can't think of a single silly or frivolous thing she ever did.
If this is a nearly universal experience, I wonder if one could use it as a way to explain roleplaying. Because if you think about it, that's pretty much what you're doing. You take what you know about your pet's personality and fill in the gaps, to create a character out of your pet, and then you roleplay that character's statements in whatever situation the pet is in. It doesn't seem like a comparably complex thing, but it is really a simplified version of the central concepts of roleplaying.
But even if you can get over the differences, I don't think you can really make much use of the similarities, if only because of how people consider it so frivolous that they probably wouldn't admit to doing it. Pity, too. So many people who don't know what roleplaying is, and so can't enjoy it or appreciate it or join the rest of us; and most of them are unwittingly doing it every day, in a very limited form.