1.A person who has committed a party foul
2. Someone who is a debbie-downer, anti-social, a loser
3. A person who ruins party's
4. Someone who does not know how to have a good time
5. Someone who is a wallflower
Juan decided to stay in and do homework instead of coming out with us on Saturday; He is such a mufflebaby.
Dan forgot to buy the cups for the root game, he is such a mufflebaby.
someone who commits a party foul.
someone who is boring, or a downer.
Lionel won't take this shot with us. He's being such a mufflebaby.