Based on obligation:
* Shouldn't: This is the most direct antonym, implying a lack of obligation.
* Example: "You should wash your hands," vs. "You shouldn't eat with your fingers."
* Must not: This implies a stronger prohibition.
* Example: "You should be respectful," vs. "You must not interrupt."
* Don't have to: This emphasizes a lack of necessity.
* Example: "You should exercise regularly," vs. "You don't have to exercise every day."
Based on advice:
* Shouldn't: This implies a lack of recommendation.
* Example: "You should visit the Louvre," vs. "You shouldn't go to that restaurant."
* Could: This suggests an alternative option.
* Example: "You should take a break," vs. "You could keep working."
* Shouldn't need to: This implies that something is unnecessary.
* Example: "You should call your parents," vs. "You shouldn't need to call your parents because they're already on their way."
Based on expectation:
* Shouldn't: This suggests a lack of expectation.
* Example: "He should be here by now," vs. "He shouldn't be here until tomorrow."
* Shouldn't have: This implies a past action that was unnecessary.
* Example: "You should have told me about this earlier," vs. "You shouldn't have bought that."
The best antonym for "should" will depend on the specific context of the sentence.