Slang for jealous.
a fun way of saying ur jealous :
"omg, don't be so jealous all the time!"
"omg, dont be so jell-o all the time!"
"omg i love your shirt! im soo jell-o right now..."
Fred: Well, I have been wanting a year's supply of jello. It's my favorite food!
random dude #2: Dude, wtf?