I have been to Ibrox 4 times actually. My uncle took me when I was younger in the Mark Hately and Ally McCoist days, he is a massive fan. It's not for me. Maybe you don't see it as much in England, but virtually all Rangers and Celtic fans I know over here are bitter in some shape or form. They try to patch it up as if its football rivalry, but its pretty much based on a religion if you ask me...all stems from that. You never see a catholic rangers fan, the same goes for a protestant celtic fan..
If you see a fella walking down the road in a ranger or celtic top, I would say 8 times out of 10 he will be a chav, trouble maker, etc..Thats how they are viewed here by a lot of people.
A man walking in the wrong part of belfast with a rangers or celtic top on could easily get lynched.
I know a lot of both, and most of them aren't the brightest spark.