Could we use instabilities instead of avoiding them? Mechanical instabilities are usually seen as failure modes. However, recent work shows they can instead be harnessed to give structures rapid, switchable, and adaptive behaviors. Snapping instabilities, for example, allow sudden transitions between stable shapes. In this talk, I introduce countersnapping, a new type of snapping instability in which a structure becomes stronger and stiffer as it snaps, giving rise to programmable stiffness, tunable natural frequency, and hinting toward the possibility of domino-like wave propagation. I will discuss some avenues on how mechanical instabilities could be used to reach structural adaptability using propagation waves.