I firmly believe that sandwiches have a top and a bottom.  I'm amazed when people don't agree with me.  The correct way to stack ingredients in a sandwich is as follows: 

1. Bottom piece of bread
2. Primary meat
3. Secondary meat
4. Vegetables
5. Condiments
6. Top piece of bread

I had a sandwich the other day that had the primary and secondary meats switched -- the bacon was underneath the turkey, and there was lettuce and tomato on top of the turkey.  After each bite, I would flip the sandwich upside down, hoping it would taste right the other way around.  No matter how I held it, it felt wrong.  What a disgraceful sandwich. 

I think there's a reason behind all this, besides my obsessive compulsive anal retentiveness.  I don't think the human palette was meant to experience ketchup and mustard as the first ingredient.  I don't think lettuce and tomatoes deserve to be the first thing to touch my tongue after a bite of a sandwich.  And although I like bacon, it's a secondary meat when it's on a sandwich, except when it's in a BLT.  I think the reason sandwiches are made the way they are is because the tongue was meant to experience the sandwich in a certain order.  It's called a turkey sandwich for a reason.  It's not a "lettuce and tomato sandwich with turkey". #food