A pregnant woman boards a bus

A pregnant woman boards a bus. After
taking a seat, she notices a man smiling
at her. She feels self-conscious and
changes her seat, but he seems even
more amused.
She moves a third time, and he starts to giggle. On her fourth move, he bursts out
laughing.
They both get off the bus at the next stop.
The pregnant woman is furious and
demands an explanation. "What exactly is
so damn funny?" "I'm sorry, ma'am," replies the giggling
man. "But I couldn't help noticing you're
pregnant, and when you first sat down,
you sat under an advertisement which
read 'Coming Soon: The Gold Dust Twins.'
Then you sat under an ad that read 'Sloan's Liniments Remove Swelling.' Then
you moved under a deodorant
advertisement which read 'William's Stick
Did the Trick.' And I just couldn't hold it in
any longer when you moved a fourth time
and sat under a tire advertisement which read 'Dunlop Rubber Would Have
Prevented This Accident.'"