The act of thinking something through
in your mind, usually a phrase or sentence, before actually saying it. This is usually advised by someone when a person starts spurting out random thoughts that make
absolutely no sense, and add no value to the current
conversation.
Guy 1:
Sometimes for to being
smarter, is for to being deader.
Guy 2: Dude, first you've
got to mentalate it, then put it out.