Period

The kindergarten class had a homework assignment to find out about
something exciting and relate it to the class the next day. When the time
came for the little kids to give their reports, the teacher was calling on
them one at a time. She was reluctant to call upon little Johnnie, knowing
that he sometimes could be a bit crude. But eventually his turn came.
Little Johnnie walked up to the front of the class, and with a piece of
chalk, made a small white dot on the blackboard, then sat back down. Well,
the teacher couldn't figure out what Johnnie had in mind for his report,
so she asked him just what that was. "It's a period," reported Johnnie.
"Well I can see that," she said, "but what is so exciting about a period."
"Damned if I know," said Johnnie, "but this morning my sister said she
missed one. Then Daddy had a heart attack, Mommy fainted and the man next
door shot himself."