NFL legend Jim Plunkett knows what SHOULDN'T happen in Vegas ... the Raiders playing there ... saying the silver & black moving to Sin City is a no-no.
Plunkett is a GOD in Raiders lore ... having won two Super Bowls with the team back in the day. So when we got him out in San Fran we needed to know his thoughts on rumors Vegas could be the team's new home.
Long story short ... he ain't with it.
Check out the clip.