When you're eating a hot dog, someone inevitably says, 'You know what's in those things, don't you'?
The response is usually something like, 'I know, I know, all the left over stuff'.

Well here's a list of the typical ingredients.
Just thought this was interesting

HOT DOG Ingredients:

Carcasses from old or thin cattle and swine
Cheeks and Jowels (The loose, fatty flesh from the lower jaw or throat)
Hearts
Tongues
Lips
Eyelids
Intestines
Ears
Nostrils
Tails
Snouts
Livers
Kidneys
Salt
Fat
Bone
Blood
Gums
...and of course...
Preservatives to keep it all "fresh"