if you mess with the bull, you get the horns

If you anger, irritate, or provoke someone enough, you will induce some hostile retaliation or emotional reaction. A: "Did you really yell at Stan today?" B: "I did, after I overheard him complaining about me to other people. If you mess with the bull, you get the horns!" Would you leave me alone, you jerk? If you mess with the bull, you get the horns—consider that your one and only warning. What, did you think I was just going to let you spread nasty rumors about me? No way—if you mess with the bull, you get the horns.