We present a new symmetry breaking that prompts gas bubbles to 'gallop' along horizontal surfaces in a vertically-vibrated fluid chamber, self-propelled by a resonant interaction between their shape oscillation modes. Their motion can be dynamically tuned via external forcing, exhibiting distinct trajectory regimes including rectilinear, orbiting, and run-and-tumble motions. The galloping symmetry breaking provides a robust self-propulsion mechanism, arising in bubbles whether separated from the wall by a liquid film or directly attached to it. Spectral analysis reveals that the galloping instability results from the coupling between symmetric and asymmetric shape modes. We showcase a series proof-of-concept demonstrations, highlighting the technological potential of galloping locomotion for applications involving bubble generation and removal, transport and sorting, navigating complex fluid networks, and surface cleaning.
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