DJOnigiri said: My best guess is that their anger has something to do with being in the heat or hot weather... and a rise in price? I'm terrible at this.
Ganguro girls are typically supposed to be bitchy and obnoxious. However, Kaibara-yuzan is the same way, and in this particular scene, I believe it's when he's complaining about the lack of gourmet sensibility of hayashi-chuka (the noodle dish they're eating). It's at this point the place where he's visiting's occupants get pissed.
So then, with this pic (not the series), we enter an imaginary "oh it's on now" between some obnoxious, often-shameless teenage ganguro girls and cantankerous Kaibara-yuzan the gourmet, who can probably stand on their level on his own.