To make crust: combine finely ground graham cracker crumbs, white sugar, melted butter, and ground cinnamon until well mixed.
To make lime mixture: combine sweetened condensed milk, sour cream, and lime juice. Mix well.
Line small muffin cups with liners. Press about 1/2 tablespoon of crust mixture into the bottom of the liner cups.
Place lime mixture on top of the crust. Fill them as high as you would like.
Preheat oven to 350°F. Bake in preheated oven for 5-8 minutes or until tiny pinhole bubbles form and burst on the surface of the lime mixture. Do not allow it to brown.
Chill bites in the refrigerator.
Top with lime slices and/or whipped cream.