No. Closest I've come was 25%, for exceptional service. I'm a flat tipper. You could be a dick or treat me like the late Princess Di and I'll still tip 20%. I used to work in restaurants and know firsthand how hard waitstaff work for the tips. I've even seen servers cry their eyes out because someone stiffed them.
Have you ever read a book on a complicated subject (i.e., astrophysics) and came away understanding it despite have never taken a class in it before?