Related Clues:

• Titter in a tweet
• Online outburst
• Texter's guffaw
• Twitter titter
• Chat-room ha-ha
• Bit of a laugh
• 'You're killing me,' in texts
• Part of many an AIM chat
• Laugh part
• Scheming giggle
• Online cackle
• Emoticon alternative
• Cyberchuckle, and a hint to this puzzle's four longest answers
• AOL guffaw
• Giggle part