Updated: Jun 14, 2021
Years ago, there used to be a dip on 680 south of Walnut Creek I think it was. Everyone knew about it, too, because it was fun to hit at 75mph.
[as Liz points out in the comments, it was just south of the Benicia Bridge]
Well... 120 out of Benton Springs connects US-6 to my beloved US-395. So when a sign announced dips next 5 miles, my interest was peaked. Increasing to 80, I was ready. Woo, woo, woo, woo, wee. And woo, wee, woo, wee, whup!
Most excellent fun!