Hi John,
My understanding is that it refers to this section of track near the state line:
http://www.railpictures.net/viewphoto.php?id=413514&nseq=17
As noted in my caption, the nickname for this curve apparently does not go back to the D&RGW freight days, but came about afterward, in the tourist era, referring to the activities of teenagers who spent their evenings parked on the mesa above the curve.
That's the story I have heard. I would certainly defer to anyone from the local area who has more detailed knowledge.
/Kevin