 Bart and Milhouse have to remain inside the Simpsons ' house when an ozone hole moves over Springfield . The two dress up as ladies and jump on the bed , singing " Sisters Are Doin ' It for Themselves " . When Homer comes in abruptly , Bart falls off of the bed and lands on one of Homer 's bowling balls and breaks his coccyx . Dr. Hibbert informs Homer and Marge that Bart will have to use a wheelchair until the bone has healed . When Bart arrives at Springfield Elementary School the following day , he finds that he cannot enter because the school lacks ramps for the disabled . As Principal Skinner considers a ramp for the school , mafia boss Fat Tony emerges and suggests that his construction company would be a good choice of company to build it . Although the new ramp system almost immediately collapses , Fat Tony informs Skinner that the construction supposedly cost US $ 200 @,@ 000 and that the school will still have to pay . In response , Principal Skinner decides to close Springfield Elementary due to lack of funds ( having used them to pay off Fat Tony and thus avoid brutal mob reprisals ) . 
