One is a moral man who grapples with inner darkness, and outer zombies, between shouts of "Carl!" The other is an unstable mercenary who toys with the fourth wall, and his opponents, between cries of "Chimichanga!" A confrontation between the two was probably inevitable because ... well, why not.
That's probably giving a little too much thought to this video mashup, which pits Rick Grimes against Deadpool using footage from AMC's The Walking Dead and the red-band trailer for the Ryan Reynolds film (so, yeah, "NSFW" and all of that).
While it's a bit difficult to imagine the two wildly different characters inhabiting the same space, it's easy to forget all of that when seemingly Deadpool dismisses Rick's impassioned pleas with, "Daddy needs to express some rage."