The application of an AC electric field to a mercury drop resulted in large-amplitude shape oscillations due to variations in its surface tension. Quasi two-dimensional (2-D) oscillation patterns were identified from the 2nd-16th modes for flattened drops under a pressure of 1G. In addition, three-dimensional oscillations were observed in low-gravity using a drop tower, with several polyhedra patterns being clearly identified, e.g., a tetrahedron, hexahedron, octahedron and dodecahedron.