McDonalds

Sure, it's not good for you (not even the salads or apple slices for the kids...ESPECIALLY not those), but people still develop near-addiction to the food here.

"Hey, it's cheap!"
You sure about that? Let's see, something cheap...The classic Hamburger: 89 cents (at the McDonalds' around here). Let's see: 1 hamburger bun (top and bottom, of course), one 1/4 lb burger, minced onions, three pickle slices, and maybe half an ounce of ketchup (being generous here). Here are some prices I found for these on GroceryGoGo.com:

Arnold Select 8 Hamburger Rolls - 8ct:        $3.19
Fresh Ground Beef - 80% Lean apx 2 lb:        $8.40
Onions White - 1 lb:                          $2.59
Vlasic Whole Original Dill Pickles 46 oz jar: $4.89
Heinz Ketchup Squeeze 32 oz sqz:              $2.69
---------------------------------------------------
TOTAL:                                       $21.76

MATH TIME!

$3.19 / 8 buns = apx          $0.40 ea = $0.40
$8.40 / 8 '1/4' lb patties =  $1.05 ea = $1.05
Onion = (guess)               $0.12 ea = $0.02
Pickles = (guess)             $0.02 ea = $0.06*
$2.69 / 64 '1/2' oz ketchup = $0.04    = $0.04
----------------------------------------------
TOTAL PRICE PER BURGER                   $1.57*

So, yes, it's cheaper for you to go to McDonalds. BUT for 68 cents more*, you can get an even BETTER burger that was made when you made it and seasoned as you like it (preferably with panko and a "secret family recipe" of herbs and spices...or steak sauce. Not to mention, you do have to factor in the drink...and why not drink some water...or as Dudel suggested, Kool-Aid.
Oh, and if you think about it, they're paying probably less than 10% on that. I actually DID choose a slightly more expensive way, as I didn't include frozen meat or bulk quantities.

*EDIT: I didn't change it in the math, but the price of the pickles wouldn't even register, as I put my price guess for a WHOLE pickle. So...yeah...the final is 6 cents off, but it's still a lot.

"They have healthy options, too, don't they?"
I'll let you believe that. It's mostly wrong, but go ahead and believe it.

"So I take it you don't go there often?"
I try not to, but like White Castle, I ate there once and get random STRONG cravings. I usually get the Cheeseburger or Double Cheeseburger...which is a little strange as I don't like beef...but then again, that's not beef ^_^