Ever had an easy time pouring ketchup out of the bottle? Join the rest of mankind having the same problem. The reason for it is that it's mostly a non-newtonian fluid in more than one way. Watch TED-Ed explain why it's so damn hard to pour it out in the video after the jump.

Ketchup can suddenly thin with the right amount of force applied, or gradually thin after a long time. The best way to pour it out is to keep the lid on the bottle, shake it up real short and sharp and then remove the lid and pour.