The phrase "crawl fours" typically refers to the act of moving on all fours, like a baby or a four-legged animal. Some synonyms for this phrase include "creep," "slink," "scuttle," and "slither." These words all refer to some kind of movement that involves using one's hands and knees to move across the ground. Other words that could be considered synonyms for "crawl fours" include "grovel," "scurry," and "squirm." All of these words have slightly different connotations, but each one can be used to describe a similar kind of movement on the ground.