Something Exciting

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 Johnny, since he sometimes could be a bit crude, but eventually his turn came.
Little Johnny walked up to the front of the class with a piece of chalk. He made a small white dot on the blackboard and sat back down.
The teacher couldn’t figure out what Johnny had in mind, so she asked him just what that was.
“It’s a period,” reported Johnny.
“Well I can see that,” she said. “But what is so exciting about a period.”
“I hoped you can explain it, but it must be exciting!” said Johnnie, “because this morning my sister said she missed one. Immediately, Mommy fainted, then Daddy had a heart attack and the guy next door ran in dragging Billy with him and screaming bad words right and left.”