Va le chercher toi-même!
vahl shair-shay twah-MEMM! Click below to hear this.*
Go get it yourself!
This sounds like sibling pushback! Not from my siblings, of course; they are both perfect, and none of us would ever say such a thing to each other. Same with my siblings-in-law.
Nevertheless, people do say these things, so this is worth learning. Get is a tricky verb to translate, since it can have so many meanings. One important translation is chercher, which is used when you want to convey the sense of fetch, look for, or pick up someone in a car to take them somewhere. If you look up chercher in a dictionary, you will find that it actually means to look/search for.
So when you say Va le chercher toi-même! you are literally telling someone to go look for the yaourt dans le frigo, but you are taking for granted that the person will also go to the trouble of grasping it, picking it up, and carrying it back to the sofa. And will condescend to bring one for you, too.
*Some mobile phones, such as Blackberries, won’t display the audio player. If no player appears, here’s an alternative link to the audio file: