The Russian word for bear, mostly a baby bear ( Cub ).
That's why the logo of the compony "Mishka" is a bear.
Also used as a pet name, very much like sweetie-pie and honey-bear
1: I just saw a mishka in in the woods!
2: I love you so much, mishka.
Jelly is a slang word that derived from the word "jealous".
It's a play on words: you're so jelly you turn into jam. Basically saying that you're extremely or beyond envious.
Mostly used in a joking manner and among females.
1: I'm so jelly I'm jam, that you're on vacation right now Beth.