Charna's Guts is the hugely popular swear in Cirque Du Freak. It is basically a vampire's way of saying "Bloody Hell!" or "Damn!". The term "Charna's Guts!" comes from the vampire Charna, who had most of his guts clawed out in a fight with a vampaneze, but who carried on fighting, and won.
To pronounce this swear: CHAR(rhymes with "car)-nah's Guts.