“Are we there yet?”

You are going on a road trip with your family. The trip takes several hours, so after an hour your kids start to get really impatient. One of your children asks:

Are we there yet?

Are we there yet?

This is a well-known question that kids ask when riding somewhere in a car, on a plane, etc. It means "Are we going to arrive at our destination soon?"

Sometimes when they want to annoy their parents, kids will ask "Are we there yet?" over and over again:

Child: Are we there yet?

Parent: No.

Child: Are we there yet?

Parent: No.

Child: Are we there yet?

Parent: No! And stop asking!

Adults will sometimes jokingly ask this question to their friends, spouses, brothers & sisters, etc. who they are riding with. 

(present-tense question) yet?

You can use "yet" with present perfect questions like these: 

Have you seen "The Hangover 2" yet?

Has she called you back yet?

It's not considered correct in formal, classroom English, but in speech people also ask simple past tense questions with yet:

Did you she call you back yet?

But "yet" can also go after a present-tense question:

Are you finished yet?

Is dinner ready yet?