I think this is the episode where they get a pool in the back of a truck, can’t remember the name.

This happens before the pool. Bart and Lisa are complaining about the heat, the ice cream man drives by saying “ICE CREAM! ICE CREAM!” They look up excitedly before he adds “WE’RE ALL OUTTA ICE CREAM!” Soon after this truck comes by and the driver is saying “Chili! Boiling hot, Texas style chili!” I quote this guy literally any time I make chili.