A Spanglish saying which means 'me too'. Instead of being forced to say 'Yo Tambien' which literally means 'me too' in spanish, you say 'mi dos' so you don'thave to go through the trouble of explaining what 'Yo Tambien' means. 'Mi Dos' is more apprehendable because the average person knows that 'Dos' means the number 2 in spanish. (If they don't, then they shouldn't be on UD.)
mainly used with great enthusiasm.
friend: I love pancakes!
you: Mi dos!
friend: Matt Damon? No way! I love him!
you: OMG! Mi dos!!