A 10:30 is a special sandwich you can get at McDonalds, but only if you order at exactly 10:30 a.m. The 10:30 is a cross between a Big Mac and an Egg McMuffin, containing beef, egg, special sauce, and McMuffin. At 10:30 a.m. McDonalds changes over from their breakfast menu to their standard menu. At this point in time they will have both fresh Big Macs and fresh Egg McMuffins available. If you order at precisely this time, and ask the cashier for a "10:30," you will be able to experience the apex of fast food. If you don't ask for the 10:30 by name you probably won't get one.
"Excuse me miss, can I get a half Big Mac half Egg McMuffin?"
"Um, I don't know what you're talking about and we stopped serving breakfast."
"Hey baby, let me get a 10:30" *wink*
"Alright." *smiles and nods*