Give us the whole sentence, please.
We’re travelling forward at, good Lord, 51 miles an hour. Now let’s assume that your brakes are new and the callipers are aligned, still, by the time we come to a stop, we’ll be occupying the same space as that Buick in front of us, an impossibility that nature will quickly resolve into death, mutilation and… oh look, they built a new put-put course.
This is Sheldon going off at Penny. You know, if you say the context it makes it a lot easier for us all. Anyway, this is humour, and unless you get the joke, it won't be of use to explain.