Related:

• His back against a rock he bore. And firmly placed his foot before
  Come one, come all! This rock shall fly From its firm base as soon as I." -- Sco...
• Please press firmly. You are making 1,000,000 copies.
• Knock. Don't ring bell. -- Seen on Pavlov's doo
• PLEASE USE OTHER DOOR.
• This door is baroquen, please wiggle Handel. (If I wiggle Handel, will it wiggle Bach?
  ) -- Found on a door in the MSU music building...
• Found on a door in the MSU music building: This door is baroquen, please wiggle Handel.
  (If I wiggle Handel, will it wiggle Bach?)...
• Krusty: So, uh, Milhouse, know any knock-knock jokes?
  Milhouse: [crying] I want to go home!...
• The opulence of the front office door varies inversely with the fundamental solvency of the firm.
• I bought a blank tape at the stereo store, and came home and put it on my stereo.
  A few minutes later there's a knock at my door. It's a neighbor complaining....