nasty-ass canned jalapeno pepper slices
Zesty is commonly found on top of the "nachos" served by concessions stands at sporting events. "Nachos", for the purposes of this definition, is zesty atop edible-plastic "cheese" served from heaters by pushing a yellow button and waiting for the "cheese "food" " to cover the stale chips provided by the company running the concession.
So named due to the prominence of the word "ZESTY!" on the gigantic can from which the archetypal zesty originates. The real brand name of zesty is lost to history, and frankly, is irrelevant.
Emphatic is "zes-tay", or sometimes described by the effects of eating the zesty. See also: explosive diarrhea