I always knew McDonald's hamburgers tasted like crap, but...

...I never thought I'd see them copping to it in an ad of theirs. Can you guess what the ad below [by Haye and Partner, Unterhaching, Germany, ganked from Ad Goodness] is selling? Frankly, my first guess was "shit sandwiches." Fossilized sandwiches? Coprolite sandwiches? Answer below ad.

( It's not really shit, just brown and wizened. )