Heres a possible better one:
So a guy tells his friend that he has found the secret way for perfect foolproof lovemaking. He says to his friend that he was always getting tired easily, so he tells the friend that he has love, waits 30 minutes then has love again during the night, and repeats this a couple times till he and his wife are satisfied. The friend decides to do this also with his wife Tuesday night, so he has love with her, sleeps, wakes up and has love with her, sleeps, wakes up and has love with her, and then goes to sleep. He then wakes up in the morning, seeing as he slept in as the clock says 8:30 AM, and he is supposed to be at work 7:00AM. As he arrives, he apoligizes to his boss about being late, and then the boss says, "Where the hell were you Wensday and Thursday?"