Dogtrousers
Kilometre nibbler
I don't think there's anything that specific. It's just that everyone takes it easy because if you did try something on (a) you would be easily chased down and (b) those tired riders who had to do the chasing would hate your guts for making them work. That's pretty much all there is to it.The gentleman's agreement relates to not attacking the yellow jersey, not improving your GC to 5th place in any event., hence not shooting off when they do a photo call, or sipping champagne early in the stage
At least, that's how it was explained by David Millar.
And as a result, there are photoshoots and whatnot early on, and then there is a serious circuit race.