McDonald’s fries are made with beef extract

This isn't even something they're trying to hide. The nutrition facts for the fries mention that they have a "natural beef flavor". Strangely enough, the fries also contain wheat and milk.

This was actually the subject of some controversy in 2001. A class action suit was filed against McDonald's for causing emotional distress to vegetarians who mistakenly ate the fries without knowing that they contain beef.