Yup, many times. I even had to stand on the outside from Nob Hill all the way to Fisherman's Wharf and it was sooooo cold! I was hanging on for dear life! When another cable car approached from the opposite direction, the operator told me, "Watch your back!" YIKES! They may not go fast, but going up and down those hills can be scary!
I love San Francisco! I would move there if it weren't so expensive!