It was at Southern Honor Wrestling's Retaliation that Jericho arbitrarily appeared, attacking two opposing wrestlers with a steel chair. As the assault continued, Jericho found himself interrupted by the entrance music of Kenny Omega, who planted his Double or Nothing foe with a dragon suplex, before hammering him with strikes.
Omega was then attacked by one of the local wrestlers, and a large scrum broke out, with the unadvertised Jericho and Omega in the thick of it.
The only AEW connection to SHW's event prior to the double surprise was that Cody Rhodes was advertised for the show. Rhodes noted in a tweet one day prior that the event was his "final independent stop", and that it was taking place down the road from where he grew up.
So there you have it: make sure you go to your local indy shows. You never know when two former World champions with a long-standing beef may show up and start throwing hands with each other.