Two pensioner are on the highway by car

Two pensioner c@uples are on the highway by car and do not drive more
than 81 km / h. 
A policeman stops the car. 
The grandfather asks, “Were we too fast?” 
Then the policeman: “No, but why are you driving so slowly?” 
Grandpa: “Can you drive faster?” 
Policeman: “I think 100 km / h you can drive quietly.” 
Grandpa: “But the sign says A81.” 
Policeman: “Yes, and what do you mean?” 
Grandpa: “Well, I have to drive 81 km / h.” 
Policeman: “No, that’s just the number of the highway.” 
Grandpa: “Oh, thank you for the hint.”

As the policeman caring asks the two retirees: “What’s 
going on with the two back? Are not the ladies good?” 
The other grandfather says: “Yes, yes, we only come from the B252.”