You can't. The second your child asks anything about the Easter Bunny, tell them it's a lie and there is no Easter bunny. It will be easier for you.
This happened about 19 years ago when my son, age 3, caught me on the Saturday before Easter and started grilling me on that stupid rabbit.
Dad, where does the Easter bunny live?
Well, I don't have a clue where he lives. I say, in the woods.
What woods? Does there have to be a particular forest? Uh, Yellowstone, I tell him.
How does he get around the world? Santa has a sleigh.
Crap. How does he do that? I should have said there were a bunch of them. I stupidly say, He hops. And immediately regret it.
I know, I that was stupid for me to say. I say, well, he's magic.
Why is he so big?
Shit. Yeah, why is he so damned big? It's kind of disturbing, a rabbit that big. I say, because he's very old.
How does he get in the house?
That's a good question. How does a giant magical rabbit get in my house? I say, I leave the door open for him.
Why does he bring candy?
I have no answer for this. What candy has to do with resurrection I can't even fathom. I pretend to be interrupted by a car driving by.
Why does he hide eggs? Does he lay eggs? Where does he get them?
Okay. This is the last straw. This Easter Bunny makes absolutely no fucking sense and I cannot defend him. He is a giant, magical rabbit that breaks into my house and leaves candy and hides eggs. How can anyone even try to make sense out of this?
I say, There is no Easter Bunny. It's me and Mom. We bring you candy and a couple of toys.
I let that sink in a while. It doesn't seem to bother him because even a three year old can see it doesn't make sense. He says,
What about Santa?
I say, Santa's the real deal. He has a backstory.
The Tooth Fairy?
I say, No. Just Santa Claus. That's the only one.