Why are people still racist against Jews?

Why should Jews be immune to offence? People constantly say stereotypical things as a joke. Saying a Jew has a big nose is like saying all american's are fat or all guys are obsessed with sex...It's a widely accepted generalization. Sometimes these generalizations are offensive. Everyone says offensive things to others, usually by name calling and we all feel offence sometimes, it's part of life! So why should Jews be any different?