Harleys Only
Hells Angels are a motorcycle club, so it's not exactly shocking that members need to own a bike—but not just any bike will do. It's a tradition for members to ride a Harley Davidson. However, some other makes are acceptable, such as Buell, which is owned by Harley Davidson. If you show up with a bike that wasn't made in America, you're going to get sent home.
No Apostrophes
We don't know why there is no apostrophe in Hells Angels, and according to their website, they don't want us to know why the apostrophe is missing. "Missing apostrophe in Hells Angels?" the site reads. "Yes, we know that there is an apostrophe missing but it is you who miss [sic] it. We don't."