Riffaterre's joke

I heard a talk by Riffattere, He said this joke was not ambiguous, because the only funny way is to read it is one way, not the other. 

"Bob makes love to his wife every Thursday. So does Bill."   

I was thinking of a variation of this. A man complain to his boss about being depressed. The boss says, when I get depressed, I take the afternoon off, go and have a martini with my wife, and take her to bed. Why don't you try it? I'll give you afternoon off. 

"How did it go?" asks the boss the next day.  Wonderful! says the man. By the way, you have a nice house.