once and for all
To accomplish the objectives in one go to the degree where it need not be done again.
Facism in Europe was supposedly ended once and for all. When people forget what it did, and the war vets are all dead, it may rise again.
Once you go Greek, that's all you seek
When you date a Greek guy/girl and it ends, you still want them even though its over because you cannot resist their Greek charm or their big Greek dick (BGD)
Person 1: "Jennifer can't get over that Greek guy she was with"
Person 2: "Yeah I know, once you go Greek, that's all you seek"
Person 2: "Yeah I know, once you go Greek, that's all you seek"