I was about to get married to Sarah but always had the hots for her sister Jane.
I drove to Sarah's place to help her with the wedding invitations but only Jane was there.

"Where is Sarah?" I ask Jane.
"She left for an errand"
So I sit down and help her sister with the invitations instead.
I notice how she keeps on smiling at me.
Suddenly she stands up and tells me:
"I must sleep with you before you marry my sister. I won't tell anyone about this! Follow me to the bedroom."

Without hesitating I stand up from the chair and walks towards door leading to the street.
When I open the door Sarah and her parents stand there applauding me.
Sarah's father shakes my hand and says:
"You passed our test! You're the right man for my daughter!"

So...the moral of the story is
...ALWAYS keep your condoms in the glove compartment of your car!