Can't vote since I wouldn't put mayo on my sandwich.
In any case, if I were working at a friggin' McDonald's, I'd be bored as Hell too. A swastika would give even butter coverage to all four quadrants of the bun and is probably a Great Leap Forward in terms of efficiency. When you're stuck with a mind-numbing, soul-killing job like working at McDonald's, I wouldn't be surprised to hear people doing far worse than this.
That's preposterous, and as someone who worked there for several years, I would have taken it very seriously had an employee done something like this.