dangerous desert

Two men meet in the desert. One of them is carrying a huge menhir on his back and the other one is carrying a phone booth. (I hope I got the word right; a menhir is a lage stone)

The one with the menhir asks the other one: "Would you please tell me why the hell you are carrying a phone booth around with you in the desert?" The one carrying the phone booth replies: "Look, there are a lot of dangerous snakes here in the desert. And in case one attacks me, I just put down the phone booth, get into it and the snake can't bit me! It has saved my life a few times already. But I can not figure out why you are carrying a menhir around with you! What is that supposed to be good for?" The one with the menhir replies: "You know, when a snake attacks me, I just drop the menhir so I can run away much quicker. That's why!"