Chachi is a minor antagonist of the Fillmore! episode "The Shreds Fell Like Snowflakes". He was a student at X Middle School who was known to be a scam artist.
According to Safety Commissioner Vallejo, he and his partner Frank Bishop were investigating a bingo scam run by Chachi himself. When they gathered enough evidence to take him into custody, they chased him to the cafeteria, where Frank dumped a vat of gazpacho to stop Chachi from escaping for good.
Unfortunately, both Frank and Vallejo learned in horror that Chachi is allergic to gazpacho, and he was sent to the hospital after suffering an allergic reaction. When Chachi's parents found about this, they furiously threatened to file a lawsuit against Principal Folsom and the school for their son's injuries unless Frank was kicked out from the Safety Patrol. As such, Frank was kicked out, and Vallejo was scared to vouch for him as he wanted to become Safety Commissioner at that time.
This incident is what drove Frank's brother Francine Bishop to plot with her friends at the X Middile School Drama Club to get revenge on Vallejo for her brother's dismissal.