Possible Clues:

• 'Don't let your boss catch you watching this' acronym
• Warning letters before a link
• Like vulgar videos at your day job, for short
• (Don't open at the office)
• Brief warning accompanying a link
• Letters of warning on internet sites
• 'Careful where you watch this,' in emails
• Warning letters on some forwards
• "Don't open in the office" letters
• [This is unsuitable for office viewing]