You cannot throw a snowball at a tree on public property.

The Law

In Bowling Green, an obscure local ordinance made it illegal to throw snowballs, rocks, or other missiles at trees located on city property. The intent was to protect expensive public landscaping and prevent rowdy youths from damaging the bark of freshly planted saplings in the winter. While no one is actively policing snowball fights today, the trees remain legally shielded.