Before we get there, let's talk about each of those concepts.
Smash
This is a fun little combo. Its invention is often credited to former Packers Head Coach Lindy Infante, but Infante himself has said that he thinks he picked it up from the 49ers. Tracking down the history of concepts is notoriously tricky business.
Smash is a two man concept, designed to stretch the zone vertically. Put another way, it makes the defense pick their poison, and it's very hard for them to be right.
It's basically a curl route under a corner route.