Jimk
A jimk is a person that does not understand when another person is joking around with him or her. They take everything seriously and are often uptight pricks that don't know how to have a good time.
Victim - "Your such a fag for playing that trick on me"
Trickster - "Fuck off you jimk I was only joking"
Trickster - "Fuck off you jimk I was only joking"