This one was in a recent Readers Digest.

Two salesmen are traveling in the country when their car breaks down.
The only house around for miles was a large mansion. They knock on the
door and a beautiful widow answers the door. Since it is early evening and
the garage will not be opened until morning, she offers to let them spend
the night in the guest bedrooms. ZZZZZZZ

In the morning they call the tow truck and leave.

About three months later salesman number one opens a letter and cant believe
what he reads. He goes to salesman number two and says:

When we spent the night at the widows mansion, did you sneak away into her
bedroom in the middle of the night?

Why, yes I did.

And did you use my name?

Why, yes how did you know?

Well, it seems she died and left me her 5 million dollar estate!