Signbank

1. Used alone in response to what the person you are talking to has said to express your disbelief that they have said this and that mean it seriously (i.e., they are not joking). English = “Come on!”, “You can’t be serious!” and so on.

2. Used alone in response to a reaction of doubt or disagreement from the person you are talking to regarding what you have just said because you think it is obvious and no one could possibly disagree with you. English = “Come on!”, “You can’t think otherwise!” and so on.