Simply insert the plastic ketchup bottle top down in a sock and whirl it like mad for a few seconds. 99.9 percent of the ketchup will be in the neck. Works for mustard too. Don't try it with glass and allow for stretch to the sock (I cracked the cap once on the kitchen counter). Maybe better performed outside. BTW, this is no joke, I do it all the time. Wife and kids are not so keen on it, but it works.