ditto. Nothing about what the OP has detailed thus far leads to any other conclusion. The OP has already admitted having no problem with jokes that marginalize various different groups of people as long as they are funny. But if its a joke that, due to the OP's personal taste, isn't found to be funny then it is clearly rascist material. Double standards imo.
I'd be extremely offended if someone forwarded me something like this. Think the general rule should be: would you be offended if someone forwarded you this about Irish people when you were living in another country? Of course you would be. That type of racist crap shouldn't be forwarded around the office (although if people want to be scumbags in their private life that's up to them).