And endearing term for a new friend that you meet that you feel comfortable around, and who you'd like to lightly prod so that they feel this way around you, and let down their guard etc.
Also, there is a strong connotation here towards the act of eating muffins, which like a good friend make you feel satiated and comfortable.
Person 1: Hey muffin breath!

Person 2: :P Heya
by 1337Gamer August 20, 2013
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