The rookie comics slapped high-fives with toddlers, hugged elderly women, and giggled as they were showered in Silly String.
With moderate fall temperatures and a clear sky, hundreds thronged JFK Boulevard and the Ben Franklin Parkway to watch baton twirlers, glittery floats, and bobbing balloons. The Garfield balloon popped during inflation, but otherwise the celebration went off without a hitch.
For Zion and his other clowning friends, it was their first time in a parade. The children, ages 10 to 15, belong to an afterschool mentorship program, U.S. Dream Academy, an organization with branches in 10 cities.
Many of the students in the Philadelphia program come from single-parent households; often, one parent is incarcerated, said Lavarr Zuber, director of the program in Philadelphia.
But on Thursday, the children, who usually talk to their volunteer mentors about homework or setting goals, had a chance to goof off in front of an adoring crowd.
Amin White, 13, of South Philadelphia, watched the girls line up with a high school band along 20th Street as his group walked to the starting point of the parade.
"When I wash this makeup off, I'm going to talk to some cheerleaders," he said, smiling. "What? I'm single."
When they reached the corner of JFK and 20th and saw the crowd - five people deep in some places - lining the street, some of them looked stunned.
The four mentors who herded the children into position helped them get over their stage fright once the procession began.
Marcus Bazemore, 23, an assistant counselor at World Communications Charter School in Southwest Center City, dashed from left to right, dancing, posing for pictures, and yelling, "Happy Thanksgiving!" as the crowd cheered.
Soon the boys were skipping, waving, and throwing candy.
Amin ran out of candy after only three blocks. So he started slapping high-fives with toddlers, teens, and adults. A few times, the yellow-wigged social butterfly hugged people, who laughed with delight.
The girl clowns seemed shy at first, three or four of them linking arms and huddling in the center of the street. One asked a mentor standing nearby whether the crowd was making fun of them.
"No, they're cheering for you because it's Thanksgiving and they're happy," she said.
Latasha Roberts, 14, a seventh grader at G.W. Childs School in South Philadelphia, said she was scared at first.
"Then I got used to it and started waving back," she said.
Unlike the boys, the girls saved some of their offerings for the latter part of the march. Once they rounded 16th Street and headed toward the Art Museum on the sun-drenched Parkway, they held their wands into the wind, sending soapy spheres over the heads of the crowd.
"Bubbles!" children shouted, jumping to catch them and calling for more.
By the time the clowns reached the museum, where women dressed in red and black danced for the cameras, most had smeared their makeup and were shuffling their tired feet. But the smiles, and the high-fives for the crowd, didn't stop.
That's when Zion saw a handshake he couldn't pass up: Mayor Nutter. One of the clowns politely tapped Nutter on the back as the mayor was speaking to someone behind him.
Nutter turned, and Zion, who barely reached the mayor's waist, eagerly extended his hand. Nutter smiled and shook hands as a small group of the students crowded around him.
"I met the mayor!" Zion shouted to his friends as they walked toward the school bus that would return them to the hotel.
For Zion, a fifth grader at G.W. Childs School, it's a moment he won't forget.
"I'm never going to wash my hand," he said, grinning.
Watch members of the U.S. Dream Academy perform as clowns during the parade at www.philly.com/Parade2011
Contact staff writer Joelle Farrell at 856-779-3237, firstname.lastname@example.org, or @joellefarrell on Twitter.