I think about this occasion frequently.
I was about 10 or 12. My Dad would always sit in this particular chair and fall asleep. One particular day, he had fallen asleep in his chair with his mouth open. I got a small glass with just a small amount of water in it and decided to let one drop of water drip into his opened mouth! He woke up coughing and sputtering. Of course, I took off running. He was so mad! But, he never made a fuss.
I thought it was funny. I think from that point on, he never slept with his mouth open, especially when I was around.
...that was my Dad...