Yissed is more than being just pissed. More like a “push me out of a window already” kind of pissed. You’re SO pissed off you couldn’t be bothered to write or pronounce the word pissed correctly.
PeterBowler in his book, The Superior Person's Book of Words describes the word YISSE v to mean, desire, covert.
On arriving at Colonel Carstair's bridge party, you give his newly nubile daughter Amanda an avuncular q.v. pat on the head, saying to her father: "Ah, I yisse this miss, I wis." Knowing your penchant for childish wordplay, he chuckles politely and you head for the card table, already one trick up.