The Prop Bets sheet that I'm handing out at my party this Sunday includes under the "will it occur" section: Manning 'Omaha' play call results in TD yes/no.
I've seen other prop bet sheets with the 27 1/2 number, as well.
FYI, if anyone wants to use the prop bet sheet I've got, it's listed here:
I'm giving these out at $5 a pop prior to the game. It's a fun thing we do every year!