¡HAMBURGUESAS! 
Check out that trilingual-ness in the title space thing!! Okay, so it's only bilingual, but English isn't one of the two languages, so...
So...
Lately we discovered that Yuugi is completely obsessed with hamburgers. I mean, we always knew that they were his favorite food and all, but only recently have we noticed that he is absolutely OBSESSED with them.
And now we're wondering, are we slow or something?
Anyway, the time that you REALLY notice how obsessed he is with them is on page 111 of tankoubon volume 1. That's when Anzu tells him and Jounouchi that she wants to go to America, and they scream:

Now, see, Jounouchi is normal and the first thing he thinks of is the Statue of Liberty. Yuugi, however, instantly thinks of...
A hamburger.
Now, I know that hamburgers are like the American food or something like that, but...
A HAMBURGER?!?!!!
Okay, that's it. You don't really need any more evidence than that.