A muffin that it looks like a group of guys jizzed on it and then another guy came and took a shit on the jizz mountain.
Can also be used as a compliment
"Yo look at these jizzshit muffins i baked"
"Dam u look like a real jizzshit muffin today <3"
When a person gets so fucked up on drugs or alcohol he or she throws up on their chest/tits. It often happens to college freshmen who are binge drinking for the first time.