Translating from the "Flooding (Net Jargon)" article helpfully tn-linked by Henmere :
Cracking Aero Parts Incident The following content was posted to the blog of a male university student calling himself "Bukuroking, King of Ikebukuro".
The blogmaster was riding his scooter when he nearly rear-ended a passenger vehicle. While he avoided a collision, his scooter's aero parts got broken when it fell over. In retaliation, he yanked the driver out of his car, and in front of his family, he jeered at him, forced him to kneel on the ground, and broke the car's own aero parts.
This led to his blog being flooded. In addition, a number of his unlawful acts came to light, including the illegally acquired license plate on his own car. In conjunction with this matter, there followed a series of protests not only on his blog, but at his school, the place offering him employment, and even his father's workplace.
As a result, the blogmaster received a reprimand from the university, and his potential employers, learning of the affair, revoked their offer. Afterward, this case even became published as an example of blog-flooding in a book discussing internet society, put out by an employee of a company associated with the unofficial employer.
So, the title means Sanae went EX-mode on Kogasa right after the fourth panel.
Just seeing this with you, Kogasa, makes me satisfied for today...♡GrgrgglrglOh!It's about time to go back.Look, look! What a beautiful rainbow!Yep.It sure is!And the rain finally stopped.
Cracking ◯◯◯
"エアロバキバキ (Cracking Aero Parts)" incident reference.
The Japanese explanation is here.