A few years ago, I left a $1000 tip at the restaurant up the street because Chrome filled out the tip field with my zip code (which thankfully merely defaulted to max $1000 instead). The tip field was off-screen, and the ordering software didn't have a confirmation screen, just a "we just charged your card $X amount" screen, which made my eyes boggle.
EDIT: Looking at the original March 17th, 2015 bug, it would have been at exactly around that time...In fact, checking my emails, this happened on March 18th, 2015. I had ordered from them several times before this with no problems (they used "chownow.com" for their ordering backend).