Dr. Quek made a routine house call to Mr. Lim, one of his elderly patients. 
He asks, "And how are you doing today, Mr. Lim?" Mr. Lim replies,
"I feel just fine, doc. But you know, it's the strangest thing. Every night
when I get up to pang jio, the bathroom light goes on for me automatically when
I open the door!" 
The doctor is worried that the old man is getting senile, so he phones the
man's son, and the son's wife answers. The doctor tells her, "Mrs. Lim, I'm
a little concerned about your father-in-law. It seems that when he gets up to
urinate at night and opens the bathroom door, the light somehow goes on..." 
At which point, Mrs. Lim yells, "Ah Seng! Ah Pa is peeing in the
refrigerator again!"