meaning something is extremely bad/sucky, derived from the words suck and delicious. Meaning that the unfortunate events/things are so bad that they would be delicious.
Mikey: Holy Shvt! Look at that girl across the bar. I would do things to that girl that are illegal in 48 states!
Tim: You can't be serious dude? I hear that cum dumpster had a train ran on her by 4 guys and gave them all the clap.
Mikey: Good looking out, she's a total Skankalicious McNasty.