It's commonly used in restaurants as well as stores. I'd say the same thing myself. In fact, when offered certain food -- as with a mention of daily specials-- it would be just as natural to say, "I'll take the lamb" as "I'll have the lamb."Does that mean that it is correct to say "I'll take it. " both in restaurants and stores, or, "I'll take it. " is basically for shopping and it would be wrong but people say that very often in restaurants so no one will think it peculiar?...kind of like saying "Me either", which is wrong but many people say it but it should be "Me neither / Neither do I"??