When someone is required to make an important decision or they are interested in someone's opinion on a matter, they will often ask the question "Hey Buddy (insert object here) Yay or Nay?" The answer "Yay" would imply that the person fully supports the cause, while a simple "Nay" would do just the opposite.

Rhyming Alternatives to Yay and Nay:
Gay! - Used when the object or the person asking the question is quite homosexual.
Bay! - Used when near a harbor.
Hay! - Used when you're really in that "LAWL HORSES" mood. Gotta love horses.
K. - Used when you're really not interested in the question.