We propose a class of metamaterials possessing an arbitrary strong elastic asymmetry, which emerges from contact interaction introduced in their architecture. The material can be made stiff in tension and soft in compression or vice versa. This asymmetry results in different wave celerities of tensile and compressive components of elastic waves. The faster component overtakes the slower one and results in their dissipative annihilation through high-frequency energy cascades. We discuss the mechanism of this damping, efficient signal-absorbing assemblies, and relevant material architectures.