Onct
Rapunzel reports a Dutch usage which is very common. We use it often in my family. We might say to a child, "Come here onct and let me wipe your face." And, as she notes, it has no precise meaning, but seems to be a sort of intensive or hortatory expression. Although a very different construction, it's similar to the Southern usage y'heah, as in, "Y'all come back real soon now, y'heah!"