Chicago hot dogs

Having always believed I didn't like hot dogs, I still felt that when in Chicago, I ought to try a traditional Chicago hot dog. Guess what? Turns out, I do like them Chicago style!

So since we got back we've been eating hot dogs occasionally and I add mustard and celery salt to mine, which doesn't make a proper Chicago hot dog, but has the best bits. I just thought to check Ocado and it turns out that they sell dill pickles! I don't like gerkhins either, but the dill pickles, those I did like. So that's one step closer to the Chicago hot dog in my own home.

I'm not sure what a sport pepper is, any ideas? Wikipedia is less than helpful.