Mountain Doo is a parody of the popular drink, Mountain Dew. The first time it appeared and was mentioned is in the episode "Peeping Mom". Bart asks Milhouse to give him the Mountain Doo, Milhouse then replies by saying that his mom thinks Mountain Doo makes you bloated.
It was also mentioned in the episode Sweet Seymour Skinner's Baadasssss Song, when Lisa tells Bart everyone needs a nemesis, she mentions that "Mountain Doo had his Mello Yello".
- Episode – "Sweet Seymour Skinner's Baadasssss Song" Mentioned by Lisa
- Episode – "Peeping Mom"
- Episode – "Mathlete's Feat"
- According to Milhouse in this episode, his mother thinks that Mountain Doo makes you bloated.
- In the ending of Mathlete's Feat, Lisa is drinking Mountain Doo and talking with a "drunken" voice.