With a post-1945 POD, make Adolf Hitler T-shirts as popular as Che Guevara ones are OTL, and with a parallel demographic. What I mean is: OTL many people love the Che imagery but don't take the meaning seriously. Che has just become a "sorta left" icon to people who vaguely like the idea of revolution but don't really understand the concept or take it seriously. (Stores on State St. in Madison, Wisconsin with Che's face in the window, I'm talking about you....)
So, what does it take to give Adolf the same image, where his face is simply a vague statement for Germany and its culture, for dictatorship, or for nationalism generally, but where the demographic that wears his T-shirts is much wider than just serious neo-Nazis... and includes, say, high school and college students who enjoy Oktoberfest a bit too much....
Disclaimer: No support of Nazism is intended by this post. I am 108 percent anti. (the 8 percent is sales tax)