When one gets extremly angry and shows triats of Don Vito.
Joe: yo jon you fucking suck at call of duty!
Jon: Arghahah jhahdshjxbajdsjsk!!!!
Joe: dude stop Going don vito on me just cause you know you suck.
I shoved my friend Josh and he dropped his ice cream, man he was Going Don Vito on me after.
Similar to an event "going down", yet when something goes DON, it shows that the event is so fantastic, and imperial that to take the time to enunciate the "W" in down it will just slow people down from arriving.
"Dude, It's "Going Don!"
"Man, It's "Going Don!"
"She saw my dick and realized....it's going don"