There are a variety of words and phrases that can be used as synonyms for the phrase "bend knees." Some common options include "squat," "crouch," "hunker down," "stoop," and "hunch." These words all refer to the act of lowering oneself by bending at the knees, and can sometimes be used interchangeably with "bend knees" depending on the context. Other synonyms might include more specific terms, such as "duck," "cower," or "kneel." Ultimately, the choice of synonym will depend on the intended connotation and tone, as well as the specific context of the sentence or statement being made.