GP’s family is from Hungary. His father is a first generation American, and his aunt collected Hungarian family traditions that she then passed on to GP. They are no longer practiced by anyone in the family, in fact, they stopped practicing most of them after World War II. However, the stories of the traditions and customs are still passed down to family members, and collected by GP’s aunt.
“On the first day of May at midnight the young men cut down lilac branches and attach colored strips of paper to them. Then they take one and put it on the roof or chimney of a marriageable daughter.”
This is a ritual coinciding with spring and fertility, as the young men court the marriageable women. I haven’t heard of putting flowers on the roof of a girl in other rituals, but it sounds like it is part of a general celebration of spring as well.