Slang among physicians, especially those in training. In verb form, it refers to ordering every radiologic and lab test imaginable to diagnose a confounding (or at some institutions, not-so-confounding) illness. In noun form (also known as cheech-bomb), it refers to the panoply of tests itself.
For example the rheumatologic cheech (rheum cheech) may consist of ordering anti-ANA, anti dsDNA, anti-RO, anti-La, anti-histone, anti-scl70, RF, anti-RNP, complement, biopsies of the lungs/kidneys, imaging of the lungs/kidneys/brain.
I admitted a patient suspected of having lupus the other day, and the attending wanted me to order the rheum cheech.