Why is Curley so mean to Lennie and George?

Curley doesn't react to George at all. He picks fights because he is a man of short stature, who is nevertheless a formidable boxer. Curley is aggressive, boastful and cocky, with a volatile temper and a tendency to provoke conflict with the weak, as he does with Lennie. He provokes Lennie because he can. Lennie can't match him with words, but he is a formidable foe in the fighting department. Part of Curley's bravado stems from anxiety over his new wife, who everyone widely suspects of being "a tramp." He spends a great deal of time monitoring her, believing her to be off with other men when she is not under his supervisiopn.