When I was in high school my late father came into my room one Saturday morning and shook me awake telling me that I had a phone call.  Now this was like at 6am.  I struggled to get up, get my robe on and hurry out to the kitchen where our wall phone was.  Meanwhile my dad had gone back to bed.  When I got to the phone, I realized that it was still hanging on the wall.  My first instinct was that my dad had hung up on whoever called me that early.  
So, I marched into my parents' bedroom and said, "dad did you hang up my phone call?"  He rolled over acting as if I had just woken him up, and he said, "what phone call"?  For a minute I was confused, then it hit me...it was April 1st!  Dad went back to sleep, and I tried too, but could not!  Now it is a good memory....I did the same thing to all three of my kids when they were in high school...great fun!