Possible Clues:

• "Take it elsewhere, lovebirds!"
• Admonishment to an overly affectionate couple
• Reaction to some P.D.A
• 'Cool it, lovebirds'
• 'Take your PDA off the street!'
• "Save it for the honeymoon!"
• Recommendation called to lovebirds
• Facetious suggestion to public kissers