Louppos’s name day is August 23, the feast of Lupus the Martyr.
Churches that follow the Old (Julian) Calendar keep the same feast on September 5 of the civil calendar. See everything commemorated on August 23.
The saint behind the name

Lupus the Martyr
August 23, Martyr, Λούππος
St. Lupus was, according to tradition, the faithful servant of the Great Martyr Demetrios of Thessaloniki. Present at his master's martyrdom at the beginning of the fourth century, he reverently kept relics of the saint, through which God worked healings among the faithful of the city.
Name days: Louppos
What to say on a name day
The Greek wish is Χρόνια Πολλά (Chronia Polla), “many years.” A call or a short message on the day is what people remember. See name day wishes you can send and what a name day is.