If the mayonnaise has been refrigerated after opening during the time it's been expired then you'll likely be okay and not get food poisoning from the expired mayonnaise.
Now if the mayonnaise was left out in the open and not refrigerated then it could have gone bad and then cause food poisoning due to the bacteria growing in the mayonnaise.
Spoiled mayonnaise may cause food poisoning but expired mayonnaise shouldn't cause food poisoning or make your sick as long as it's been in the refrigerator and kept cool during that time.