Lazy stereotype is a word generally use to describe a certain group of people, community or society as being lazy, not ahardworking and not ready to improve on themselves.
The statement is sometimes derogatory and can cause conflicts in the society. For example, "Those Yorubas lacks trust, the hausas are better than them.
Another lazy stereotype example is when you talk people down even when you don't know how they're managing there daily affairs.
However, the word is an harmful and unfair judgements of others so care should be taken whenever we are talking so as not to tarnish the image of other cultures while trying to justify your own assertions.
