Ethan is a boy Ally met in the Halloween store in the episode "Costumes & Courage." He is played by Troy Osterberg.
He wanted a Charles Lindbergh costume when Trish was working there, but she gave him a random pilot costume instead. When Ally shows her cute nurse/Florence Nightingale costume to her, she persuades her to introduce herself to him. When Ethan recognized her as Ms. Nightingale, Ally jokingly said "Good ol' Flo," and winds up embarrassing herself.
He sees her again at the Starr Records Halloween Party only this time dressed as Galexis Nova, and he doesn't recognize her as Ally. As he asks for her phone number, she gets so excited that she leaves the balcony and forgets to give him her number.