How to remember which function is concave and which one is convex? I always struggle to remember when a function is convex and concave:

Do you have a particular trick to help you remember this? 
My trick is based on the Spanish phrase "No cabe", pronounced nô ˈka.βe, which sound just like "concave". "No cabe" means it does not fit. Thus, whilst you can put something into a convex function (e.g. think of a bowl), you cannot put something into a concave function. Hence the relation. 
I am curious on what other, perhaps more efficient methods people use.

conVex - V looks like the convex function :)
