Verb. - The action of forming a portmanteau.
(Note: Porteau is an example of a internal portmanteau, where a word is shortened or apocopated by joining its two ends at a common letter - here 't'.)
On many sitcoms, an easy way to make a joke is to have a character porteau new words.
Examples: Friends - "Fricken" (fried chicken) - Chandler
............... HIMYM - "Visitivity" (vision creativity) - Barney