An inability to walk due to an equilibrium malfunction as a side effect to alcohol consumption. The individual possessing the schwavelegs will often not know what's wrong with them. Sometimes schwavelegs can be countered with weight, for example, carrying a cooler.
Dave - "I keep falling down!! What's wrong with me?"
Jon- "I think you caught a case of SCHWAVE LEGS. Your equilibrium may be off from those tequila shots"