KOREAN LESSON! WOO!
So there is a new popular phrase in Korean that is "핵노잼" (heck - no - jaem)
Let me break it down:
핵 - it means nuclear like SUPER BIG AND POWERFUL
노 - literally 'no' in english
잼 - to say 'interesting/funny' you say 재미있다 (jae-mi-it-da) which can be shortened to 잼있다 (jaem-it-da) and then just finally '잼' (jaem)....which sounds a lot the word jam....
so 핵노잼 = SUPER POWERFULLY HAVE NO FUNNY-NESS
aka YOU HAVE NO JAMS. NONE.
so rap mon was probably direct translating that phrase and now we make jokes about strawberry jelly so there we go. i love our lost-in-translation-love.