I suspect this is the connection. It’s an extract from an article in the online magazine ‘surfer.com’, talking about Ed ‘Big Daddy’ Roth, the cult custom car designer/builder:
>>>But Roth was also a cartoonist, and to fund his car-building, he started hawking T-shirts at car shows where his latest creations were on display. Hit it big in 1963 with Rat Fink, a hopped-up, bug-eyed, sewer-green monster rodent–Roth’s hairy-middle-finger answer to Mickey Mouse. Wasn’t a 14-year-old boy in America who didn’t either have a Rat Fink T-shirt or want one. Parents and teachers? Not too stoked. Moms threw away Rat Fink tees by the thousands. School-wide bans were enacted. Sales, naturally, doubled.
Roth, triumphant in his newfound fame as the anti-authority ringmaster–going so far as to dress the part in top-hat and tails–looked around for some more outrage to cultivate. Surfing! Of course! In 1965, Roth unveiled the Surfer’s Cross pendant–a replica of the German military bravery medal that had nestled in the sock drawers of people like Hitler and the Red Baron. Six months later the Surfer’s Cross was country’s hottest novelty item: a Rhode Island plant was shipping 24,000 units a day, to corner variety stores in the Midwest, all the way up to Bergdorf Goodman in midtown Manhattan.
Time jumped all over the story. The Surfer’s Cross, as the magazine pointed out, stating the obvious, was mostly a way for teens to Dutch rub their Moms and Dads. “It really upsets your parents,” a 15-year-old surfer from Palmdale told Time. “That’s why everybody buys them.” Roth posed for his Time portrait in Levis and a plain white T-shirt and a leering expression, astride a moped, his Surfer’s Cross dangling from his neck to rest gently on his beer gut. What was next for Big Daddy? A plastic copy of the Wehrmacht iron helmet. “You know,” Roth said with a grin, “that Hitler did a helluva public relations job for me.”<<<
If you Google "surfer iron cross" and click on "images", you'll see loads of variations... not necessarily all from Roth.
PS: Despite claims to the contrary by various ebay sellers, none of these things dates before 1965 when Roth started the cult. His original Nazi 'inspiration' was intended to be provocative and rebellious, but of course the iron cross, as a German decoration, predates WWII and the Nazis. The Roth cult was widely copied and imitated thereafter, as well as embracing WWI, but the 'wartime' dates on these pieces are spurious.
