Cr2Ge2Te6 is a van der Waals ferromagnet with a Curie temperature at 66 K. Here we report a swift change in the magnetic ground state upon application of small DC electric current; a giant yet anisotropic magnetoelectric effect; and a sharp, lattice-driven quantum switching manifested in the I-V characteristic of the bulk single-crystal Cr2Ge2Te6. At the heart of these observed phenomena is a strongly anisotropic magnetoelastic coupling that enables strongly anisotropic responses of the lattice to application of electric current and/or magnetic field, which explains the exotic phenomena in Cr2Ge2Te6. Such a rare mechanical tunability in the magnetic semiconductors promises tantalizing prospects for unique functional materials and devices.