I heard this from a friend of mine but I'll tell it from my perspective.

This year was my sister's turn to host Thanksgiving. My mom arrived at her house early to help her manage the baking. When my sister went on a run to Wal-Mart to pick up some supplies, my mother stuffed a cornish game hen inside the turkey. When it came time to eat, my sister proudly started to slice the turkey and discovered something hard in the middle. She cut it open revealing the game hen. "Oh my God! You cooked a pregnant turkey!" My mother yelled.  My sister, appalled, immediately started crying hysterically. It took us 3 days to convince her it was a prank and that turkeys lay eggs.