It would be chanting the name of a local sports team. This is something mayor Parker of Philly has managed to fuck up, chanting E L G S E S instead of E A G L E S because she is dumb as a rock and drunk as a skunk

OP explained the Parker aspect of the joke, but as for the Jets, their fans chant “J-E-T-S JETS JETS JETS!” in a similar fashion to how Eagles fans chant “E-A-G-L-E-S EAGLES!”