Possible Clues:

• 'Ermagerd,' in shorthand
• 'Srsly??!!'
• "Srsly?!?!"
• Text-speak gasp
• 'Srsly?!?!'
• Abbr. followed by '!!!!!1'
• Texter's "Heavens to Betsy!"
• 'I can't believe that!' in a text
• Exclamation often followed by multiple exclamation points
• 'I don't believe it!'