When I was in high school my aunt once handed me a wine glass and said, "could you throw this in the sink." A second later the wine glass shattered on impact. She wasn't joking, but my point is I often take things too literally as well.

My family had our own unique sense of humor at home, and when I tried to recreate it elsewhere people would react as if I was just an idiot or naive... they didn't realize I was joking.

I've heard humor defined as the juxtaposition of two overlapping but incompatible frames of reference, or rather the introduction of a competing version of reality.

Also just found this on google... This person defines humor as affective absurdity, which occurs when a moral principal is violated. It is interesting...
http://www.tomveatch.com/else/humor/paper/humor.html