Mother in law and son in law

A man returned from work at night and heads straight to the bedroom to make love to his wife.
When done, he went straight 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: "Aahh! That was my mother in the bedroom, she was so tired when she arrived so I let her sleep in our room. Alarmed, she ran to her mother and asked her why she didn't say anything when her husband was making love to her.
Mother replied: "you know me and your husband dont talk"