Impotent bus driver

The impotent bus driver goes to see his doctor. He wants some Viagra, but he doesn't want his wife to know about it. The doc prescribes it for him, he heads to the pharmacist, who fills the prescription. Home is a good hour away so the bus driver quickly downs one of the little blue pills. When he gets home, he doesn't even have to tell his wife with words. That twinkle in his eye speaks volumes. They tear off each others clothes and are
quickly in bed.

He manages to "rise to the occasion" three times. "Three times!" He expects his wife to be delighted, but instead, she seems rather sad. "What's wrong, dear?" he asks.

"I think your job is taking over every aspect of your life and it's doing  you in," she sighs.

"What do you mean?"

"I mean, even our sex life is like the bus service. Nothing for ages, and then three come all at once!"