There was another McDonald's on the way, so I figured I would just go in there and tell a small, tiny lie that I asked for no onions but they put yes onions. I knew it was wrong, a little bit. I mean, I figured they'd be losing like, a dollar or less. Small beans. So I walked into the store with my bitten burger in hand and tried to be polite (because I knew I was a liar):
"Hello, can I help you?" He was the manager.
"Hi. I was just in here and I ordered a burger with no onions, but I guess you must have accidentally put some on there. If it's no trouble, could I please get a new burger without? Thanks :) "
"No problem. Just one moment." I was pretty sure I was going to get my onion free burger without incident.
He turned around and took a few steps to the kitchen and yelled "Hey!" All the cooks (all Hispanic) looked at him and he held up and displayed my lie of a burger while saying something in Espanol. He then violently threw it into the trashcan and started going off on them in Spanish. A lot. And loud. They all looked like beat puppies afterward, and sullenly (but quickly) made my "corrected" meal, and it was all my fault that those poor workers got that verbal flogging.
I got my food, said thanks without looking him in the eye, and left. I felt pretty bad. So unless you REALLY don't like onions, I don't recommend trying this.