There's no context for that in the song; and for the benefit of our non-American members, dropping a ketchup bottle in moments of surprise and shock is not an American idiom. I doubt any American on this thread has heard of that before now. And I also doubt anyone here seriously believes that the resemblance to a blood spatter is a coincidence.
I never said dropping a ketchup bottle was an American idiom. I said eating ketchup with fries is an American idiom. I said dropping a glass of water (or anything really) is a stock, old-school, slapstick gag. I'm sure plenty of people around the world, including Americans, are familiar with that.
I suppose some could interpret the ketchup as a blood splatter if they were looking for yet another reason to perpetuate an attitude of victimhood. I remember years ago, there was a TV commercial for Hefty trash bags. A white lady in suburbia takes a bag of trash out to the curb, and a black sanitation worker picks it up and tosses it into the back of the truck. They smile at each other and wave. A few black folks claimed that commercial was racist.
Besides, blood splatter patterns have unique characteristics because of the consistency of blood, and the fact that it is under pressure inside the body. Splattered blood doesn't just come out looking like a blob. It typically includes directional patters. Of course now someone is sure to come up with a picture of a blood stain that looks just like the ketchup to "prove" me wrong.
People see what they want to see.