Possible Clues:

• For what it's worth, that's what musical mokes do, perhaps
• What the mokes would be doing with a heehaw
• What those with long ears can do when they get to Bray
• They're so silly so to be reckoning the value of such an invoice
• Reckoning that only the silly ones become vocalists
• The reckoning of what the donkeys will do when they get to Bray
• Getting value for the donkeys when they go 3 down?
• A reckoning that they may give one a silly song
• How silly of them to make a song about the reckoning!
• What they do when they get to Bray?