When referring to someone you think of as appealing, usually a guy, he can be called a 'Muffin'. But when you find a really cute guy, he is sometimes worth more than the simple two syllable word of 'muffin'. Worth so much more, in fact, that he deserves another syllable to the word 'muffin'. Thus equaling muff-fuff-in.
"Oh my god. Jacob is my Mr. Gorgeous, but TOMAS oh my god, he is my MUFF-FUFF-IN."
"Dude. Look at him. He is totally worth more than just 'muffin'. He's a friggen MUFF-FUFF-IN."