I know exactly how you feel. Whenever if I try to add a joke to a group conversation, all the smiles and laughs immediately stop whilst everyone patiently waits for me to finish. Once it is finished, the delivery was so butchered they often miss that it was even a joke, either way no one laughs and the mood is totally killed. If I try to contribute a short story or something (no way am I attempting a longer one), afterwards I just get "oh right" as they change the subject - a totally different reaction to anyone else. I can never feel part of a group like that.