Related Clues:

• Lend an ear
• Become a soldier
• Join forces?
• Join up
• Take the king's shilling, as Brits once said
• Start of "The Midnight Ride of Paul Revere"
• Informal conversation opener
• Teacher's request
• Take heed
• Please Uncle Sam
• 'You're not paying attention!'
• 'Pay attention!'
• Obtain, as support
• First word of 'Paul Revere's Ride'
• 'Hey …!'