Possible Clues:

• When tripled, a Seinfeld catchphrase
• Et cetera, according to "Seinfeld"
• When tripled, 'etc.'
• When tripled, phrase spoken by 25-Down
• When tripled, 'Blah, blah, blah'
• 'Blah' alternative
• Part of a phrase similar to 'blah blah blah'
• When tripled, "et cetera"
• "And so on" word
• 'And so on' word