The Wikipedia redirect is apparently dead (https://en.wikipedia.org/?title=Shadow_clone&redirect=no) and the main page for Naruto doesn't show anything about shadow clones.

Care to explain the reference? Do people dress up like a character from the TV show and help out people or what's going on?

The reference is that the anime character "Naruto"[0] wears the same colors and roughly the same uniform as a Japanese recovery worker[1].

During disaster work, you see swarms of recovery workers and the joke/reference being made is that this looks like Naruto doing a "shadow clone" technique.

[0] https://i.redd.it/psseu93j62la1.jpg [1] https://sendai-resilience.jp/media/images/efforts/case31_ima...

It's an ability from the show: https://naruto.fandom.com/wiki/Shadow_Clone_Technique.