Halloween parades are supposed to be fun and a way to give kids extra candy. Kids attending this parade did get some extra candy, but not exactly what they wanted. A few of the floats was throwing out packs of candy, consisting of little, male genitalia-shaped candies. One of the rules for this parade is that costumes and floats can't be sexually suggestive or explicit, and this definitely violated that rule.
Pranks on Halloween are a regular thing, and relatively speaking, this is pretty harmless. No one was hurt and there was no property damage done, and parents could just throw the candy away. Having said that, throwing phallic-shaped candy to kids is a really stupid prank because, you know, they're children. Maybe throwing phallic-shaped candy to adults is funny, but throwing them at kids definitely crosses the line.