WHO IS TO BLAME?

A man returned from work at night, and heads straight in to his bedroom as usual, to make love to his wife.
When he is done, he went to the kitchen to fetch himself a bottle of cold drink, only to find his wife there looking for something in the fridge.

He asked his wife how she quickly made it to the kitchen,when they've just finished making love.

His wife screamed: ''Aaaaaaaahh! That is my sister in the bedroom, She was so tired when she arrived, so I let her sleep in our room''.

Alarmed, she ran to her sister and asked her why she didn't say anything, when her husband was making love to her. Sister replied: '' you know that me and your husband are not in talking terms.