"We had a funny guy with us in Korea. A tailgunner. They blew his brains out all over the Pacific. There's nothing funny about that."

According to the Wikipedia page for A Christmas Story we know that Ralphie is nine years old, and then we find this:

Director Bob Clark stated in the film's DVD commentary that he and author Shepherd wished for the movie to be seen as "amorphously late 30s, early 40s," but a specific year is never mentioned.

Since it doesn't mention WWII at all, let's assume the year the movie takes place in is one from 1937 to 1940, meaning Ralphie would have been born between 1928 and 1931.  This means that when the Korean War started he would have been between the ages of 19 and 22, making him a prime candidate to have served in Korea.

In other words Ralphie, who is obviously a funny guy, could've been the tail gunner from THIS SEINFELD episode.

Is your mine blown?