I am assuming that the assignment requires an essay on the topic of a time where "your big mouth" got you into trouble. There are multiple ways in which this topic can be handled.

Narrative

Most likely the most common essay chosen for a topic like this, the narrative essay tells a story. The only essay where it is appropriate to write in first person (I), this essay uses a chronological approach to tell about a time where "your big mouth" got you into trouble. A chronological approach defines a time-line (what happened first, second, etc.).

Cause and Effect

A cause and effect essay could also be appropriate for this topic. A cause and effect essay examines the cause of something ("big mouth") and what happened because of it (effect). The approach for this essay could be either emphatic or chronological. An emphatic approach offers the reader the least impactive information to the most impactive. For example, the essay would begin explaining about how you may have been embarrassed (least impactive) and move onto how you hurt your mother (most impactive).

You could also use a causal chain approach (which is similar to chronological). With this approach, you will explain how things snowballed because of "your big mouth." For example, you could talk about how the refusal to spit out your gum in the classroom led to a three day suspension (yep, it can happen). In this, you would detail each cause and effect as each resulted from the previous cause.

Refuse to spit out gum--warning--next time, refuse...principal's office---next time, refuse...detention---next time, refuse...suspension. See how it works?

I have included a link below to a site my students use for their essay writing. OWL is a very comprehensive site which normally can answer all essay writing questions.