Calvin often lies about what he has for lunch. His many "lunches" have included a thermos filled with phlegm, "living" peanut butter sandwich, and cigar butts. Susie has nearly always gotten revolted at this.
Sometimes Calvin gets cafeteria food, which looks mostly the same as his dinner. He combines his "stunts" at home with normal disgusting lunch claims. Unlike dinner, though, he has managed to survive while eating it and it does no harm to him.