When an emergency keeps Marge from taking Lisa to an about-to-close museum exhibit, Lisa tries to take the bus instead and ends up in an unfamiliar part of town.

!! Tropes:

* Area51: Or rather, Area 51-''a''.
--> "You are here. We are not."
* BaitAndSwitch
* {{Balloonacy}}: Subverted when Homer needs to get up high to spot Lisa. "Oh, I hope this works...these are for you if you let me use your cherry-picker."
--> "Well, I've already got some balloons - but they're not this nice. Deal!"
* IfIHadANickel: Dr. Hibbert subverted the trope. He replaced "a dime" with the amount of money he usually charges for the kind of medical procedure performed on Bart.