Related Clues:

• Pun reaction, perhaps
• IM guffaw
• Modern lead-in to cat
• Text giggle
• 'OMG ur a riot!'
• Alternative to :-)
• Online ha-ha
• 'U R so funny' alternative
• Cyberyuk
• "I'm chuckling audibly," in email
• "OMG ur 2 funny"
• "Ha-ha," in email and texts
• Audibly amused, online
• [I crack myself up]
• Texter's "What a riot!"