I always loved the song "Pink Elephants," but the first time I watched Dumbo as an adult I was kind of shocked that the whole thing is a drunken delusion.
Dumbo isn't the only classic Disney to involve drunkenness, or to make it humorous.
Check out Sir Hiss from Robin Hood at 3:30
The Kings-and the Page-drink a little too much in Sleeping Beauty
"Let me fill up your glass-that glass was all full!" Heehee
And of course, Gaston's tavern song.
LeFou: More Beer?
Gaston: What for? Nothing helps. I'm disgraced.
LeFou: Who, you? NEVER! Gaston, you've got to pull yourself together!
In addition to these, David Koenig cites 12 other Disney films which include characters drinking: Pinnochio, Fantasio, Saldos Amigos, Make Mine Music, Adventures of Ichabod and Mr. Toad, Sword in the Stone, Aristocats, Rescuers, Pete's Dragon, Great Mouse Detective, Who Framed Roger Rabbit, and Hunchback of Notre Dame. Pocahontas was mentioned but dismissed as not qualifying for "heavy drinking."