If they hit, slap, push and shove you around; threaten to hit you, kick, punch. If they are flirting with other girls or they don't keep dates with you. If they seem to just be around you for sex, but never take you any place. If they don't introduce you to their friends (or family) or don't want to mingle with some of your friends on occasion. If he lies about important things in your life. If he refuses to work if he's not in school or college.