no Latin translation for “Y’all come back ya here!” …

… or even better “Have a good weekend. Go Panthers!”.

The Holy See has approved three alternatives to “Ite, missa est,” the final words said by the priest at Mass. Cardinal Francis Arinze, prefect of the Congregation for Divine Worship and the Sacraments, today notified the participants in the synod of bishops on the word of God about the new alternatives. The final message is currently rendered in English: “The Mass is ended, go in peace.”
The alternatives are in the revised third “editio typica” of the Roman Missal, which was printed last week, the cardinal said.

The alternatives are:

“Ite ad Evangelium Domini nuntiandum”
“Ite in pace, glorificando vita vestra Dominum”
“Ite in pace” with “alleluia, alleluia” added during Easter season.

In English, these could be rendered along the lines of “go to announce the Gospel of the Lord”; “go in peace, glorifying the Lord with your lives”; and simply, “go in peace (alleluia, alleluia).” [source]