The Far Side - One strip features anthropomorphic ketchup bottles are at the movie theatre. The gag is that they're watching a horror film, in which an on-screen ketchup bottle is broken and oozing in the street. A father bottle tells his son, reassuringly, that "that's not real ketchup" in the film. Of course, in real life ketchup can be used as fake blood, hence the joke. This stops being funny, even by Gary Larson's morbid standards, when you think about it for awhile and wonder what they're using INSTEAD of ketchup.