"Chi-co-ree!" is the highly-enunciated catchphrase of Motormouse on Motormouse and Autocat, used to express.disbelief or astonishment. As spoken in character, the word is three distinct syllables, stress on the last such.
The term is derived from the coffee additive, which Wikipedia describes thus:
Root chicory (Cichorium intybus var. sativum) has been cultivated in Europe as a coffee substitute. The roots are baked, ground, and used as a coffee substitute and additive, especially in the Mediterranean region (where the plant is native). As a coffee additive, it is also mixed in Indian filter coffee, and in parts of Southeast Asia, South Africa and southern United States, particularly in New Orleans. It has been more widely used during economic crises such as the Great Depression in the 1930s and during World War II in Continental Europe. Chicory, with sugar beet and rye, was used as an ingredient of the East German Mischkaffee (mixed coffee), introduced during the "East German coffee crisis" of 1976-79.