Possible Clues:

• WTF go-with
• 'wow r u serious!'
• 'Wow,' when texting
• 'Holy cow!,' online
• 'Get. Out. Of. Here!'
• Texter's 'No freaking way!'
• Texter's "Mercy me!"
• Texter's 'I'm shocked!'
• Online "Jeepers!"
• 'Wow!,' in a text message