Is it really so wrong?

OK, I've lied to my kids. I know it is wrong, but it is also kinda funny. My kiddos always wonder how mom always knows what they are up to. So I have convinced them that I have eyes in the back of my head - literally. They have spent hours digging through my hair trying to find them, trying to figure out why daddy doesn't have them, and wondering if they will ever get them. They also like to test me to see if they are working. Funny thing is, they always choose to test them while I am fixing dinner. That is my trick. They are too short to realize that I see their reflection in the microwave door which is above the stove. They test me to see if I can tell which one has come up and smacked me on the backside or what kind of crazy dance they are doing. Everytime I tell them precisely what they are doing and who is doing it they try to make it more challenging. It is quite entertaining to me and certainly helps keep them in line.

So my question is: even though I know lying is wrong and they are learning by my example, is this one OK to keep?