It can't be that you didn't think it was funny. If that were the case then Susan would be disappointed.
Was it the bad words?
Bad words are like friends to Susan, they help her get through the day even if someone else is saying them.
The contemporary slang?
Susan didn't get it either so she applied the same strategy that she uses with Shakespeare and the Spanish people at work; she relaxed her brain and was able to understand every third word, picking up the gist of things.
However, for a more complete understanding you may choose to refer to Rap Genius.
Surely you're not protesting because Susan's BLAHging has been spotty? Well, that's not fair! Sometimes a person has to work long hours then come home eat a bowl of cereal and go to bed in their clothes.
Susan's not perfect, if she were then she wouldn't BLAHg, she'd just be out showing everyone how to do everything right.