So fucking hilarious:
Have someone dressed up like Moses deliver the invitation worded like the 10 commandments--e.g. Thou shalt have no other dates before me, Thou shalt be ready at 7 pm on the 23rd of May, 1999, etc. (To answer this invitation, you could make a pan of Red JELL-O with the answer at the bottom in the middle--so that the person would have to part the "Red Sea.")
That mormon site is a gold mine of comedic snot