First you buy a turkey and a cornish game hen.
Then you hide the turkey and bring in the game hen and tell the kids it's a dehydrated turkey, all you have to do is soak it over night.
Fill the sink with water and put in the game hen.
Then while they are sleeping, remove the hen and replace it with the turkey.
The next morning show them the turkey and say " see isn't that cool?" and wait for the look on their face.
This will also work on blonds.
If you want to take it a step futher and don't mind paying for therapy you can put the game hen inside the turkey, so when the wife goes to stuff it you can say "OMG that turkey was pregnant".
