Originally Posted by jpv

let the pro explain it to you...

The glass bottle has a magic "57" etched in the glass where the bottle starts to get narrow. You need to hit this "57" as you are shaking the ketchup onto your plate. You don't need to shake the bottle hard or hit the "57" hard. If you do it gently it will come out smooth.

No more need to shake the bottle hard then having a massive amount of ketchup suddenly pouring all over your food.