IMPOSSIBLE TRIVIA: McDonalds Added this in 1968? Still No Answer! See the Hint

The Lite Rock Impossible Trivia question heads in to the third day Tuesday @ 7:20a.m.  If you come up with the answer, I'll give you tickets to see Sheryl Crow live at Caesar's Atlantic City August 9th, tickets to the American Idols Tour at Boardwalk... Hall on September 7th, and I'll throw in lunch at Dino's Subs in Northfield.

The question:  McDonald's Restaurants added this for the first time in 1968.  What is it?

I gave this hint ...It's NOT a menu item.

Give me your best guess Tuesday @ 7:20a.m. on the Lite Rock Morning Show