The Shrink Ray is an invention that Kin made that appeared in the episode Inn Err Face. Trina used this invention on Grojband's instruments, thinking it was a flamethrower, and instead shrinks them (unaware that Kon was inside his drumset). A chain of events then make him fly into Trina's mouth. Corey, Kin, and Laney had to try and get him out of there before the affects wore off.
The shrink ray is a gray trapezoid shaped remote with a red button on it that also serves as a dial. It has a red laser pointed on it that ejects a bright white flashing light when it zaps things.