The "dry" part means you're not expressing the emotion of laughter. In a t.v. show there might be someone making comments that are funny, but neither the speaker or listener are laughing, but there is humor in the situation, and you can sometimes hear the audience laughing. A classic example is the comedian and actor Bob Newhart, as Derrick points out. Here is a video example of Newhart http://www.youtube.com/watch?v=NU3IPSAys8s

the kind of humor that is ironic or sarcastic. It tend to be unconscious of the listener(s) feelings. Pretty much the kind of jokes that british people have!

Humor that is not obvious or unexpected. Bank shots. Can be uproariously funny or hopelessly mundane. Robin Williams is a smack em between the eyes comedian while Bob Newhart has a drier wit.

dry humour is humor not funy, it's not natural, and people can't laugh/smile with this.

yes, something like this.