How do I teach my almost 3yr old what a lie is? See lately my daughter will tell us she has to use the bathroom but when we rush off the high way or stop everything in the store or even better when she is in time out to take her to the bathroom she doesn't have to use it. Because she is only 2 I don't feel the need to punish her for her lies Due to the fact the she don't understand what a lie is, YET at the same time I'm allowing her bad behavior cause I'm not sure how to explain a lie.