Possible Clues:

• 'Yowzers!' in texts
• Textspeak abbr.
• WTF relative
• '___ WTF!??!!'
• 'Whoa!'
• 'Holy cow!' online
• Tweeter's "Wow!"
• Tweeter's 'Wow!'
• Texter's "Egads!"
• Texter's "Lordy!"