Related Clues:

• Contents of some plain brown wrappers
• Tom Lehrer song
• Obscene material
• Dirty literature
• No-no on office computers
• Lewd material
• Obscenity
• Dirty reading
• Soot particle
• Certain fungus
• Tom Lehrer's anti-censorship song
• Carbon black, e.g.
• Pornography
• X-rated stuff
• Popular website genre