This one is better..
A kindergarten teacher one day is trying to explain to her class the definition of the word "definitely" to them. To make sure the students have a good understanding of the word, she asks them to use it in a sentence. The first student raised his hand and said "The sky is definitely blue". The teacher said, "Well, that isn't entirely correct, because sometimes it's gray and cloudy".
Another student says, "Grass is definitely green." The teacher again replies "If grass doesn't get enough water it turns brown, so that isn't really correct either."
Another student raises his hand and asks the teacher "Do farts have lumps?" The teacher looked at him and said "No...But that isn't really a question you want to ask in class discussion." So the student replies, "Then I definitely shit my pants."