'Jang' is a noun meaning 'testicle' that has many uses and derivatives. When used in the plural ('jangs'), it refers to the balls as a whole, thus including the scrotum.
Its most diverse and most used derivative is it's verb form, 'jangle'. Strictly defined, this means to strike a male in the balls but 'jangle' has seen other uses resultant of its noun form, 'jangler' (see below). Thus, when used with a direct object (generally a name), 'jangle' means to strike said direct object in the balls. However, when used intransitively, it means to act like a jangler (definition two).
'Jangler' is the gerund noun form of 'jangle'. It has two meanings: first, it is more strictly defined as one who strikes males in the balls. Less strictly, however, it can also be used as a label for one who is equally distasteful as a nut-puncher, generally one who is arrogant, deceptive, or foolish.
"My jangs are itchy today."
"Whoa! Did you see how hard Frank just got jangled?"
"Look at Roger jangling around over there."
"Protect your balls; I hear there's a jangler about."
"Jon just told me he can bench more than that body-builder. What a jangler!"