Script (guión): Idioms, ‘bad mouth’. If you bad mouth someone you say negative things about them. There was a guy in my class at school who was always bad mouthing everyone, other students, teachers, any one he could think of. This came back to haunt him as one day he was bad mouthing a teacher in the class and he began to start to do an impression of the teacher.
‘Oh, this is the blackboard. Today we're going to learn about mathematics and err.’
What he didn't realize was that the teacher had walked in behind him and was waiting there for about two minutes and you should have seen the look on his face when he realized.