Teacher: Joe, can we talk about your test?
Joe: I know. I did terribly. But I'll do better next time.
Teacher: Isn't this the third one you've failed?
Joe: Yeah, so?
Teacher: Well, maybe you should stop burying your head in the sand and admit you need help. If you fail another test, you won't pass the class.
Joe: Oh wow. Yeah, I guess I do need to do something.
Teacher: Why don't you go down to the tutoring center tomorrow? I hear they have some really great math tutors that should be able to help you.
Meaning: The idiom "to bury (one's) head in the sand" is used when someone is ignoring a bad situation. The idiom is based on the idea that ostriches bury their heads in order to avoid danger; however, this is actually a myth as ostriches do not hide in this way. Here is another example:
Tricia: I finally paid off my credit card.
Val: That's awesome! How did you do it?
Tricia: Well, for a long time I just buried my head in the sand about how much debt I had, but one day I finally added it up and realized I had $20,000 in credit card debt.
Val: Wow! That's a lot!
Tricia: Yeah. Once I finally admitted how bad it was, I quit using my cards and paid off as much as a I could each month. It took me a couple years, and it was really tight, but I'm so glad I did it.
Meaning: In this example, Tricia uses the expression to explain the she was ignoring the amount of credit card debt she had.