Honestly, people

If you don't want people to be horribly disappointed, you:

-don't call an evening event a "cocktail evening" if there aren't going to be alcoholic drinks. "Cocktail" might also mean "appetiser", but that isn't the most common definition.

-don't call an event a "ball" if there won't be dancing or food. People performing short songs or skits on stage is generally known as a variety show, not a "ball".

-don't title an email to grant applicants, "Recipients of national grants 2008" if the content of said email is, "...will be notified sometime in the next few weeks."

It's not rocket science!