Top definition
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.
by ehhhh412 March 20, 2011
Get the mug
Get a mufflebaby mug for your mother-in-law Beatrix.
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.
by Team Honda Civic March 21, 2011
Get the mug
Get a Mufflebaby mug for your brother Georges.