This idea likely comes from fan-made content, jokes, or possibly misunderstandings of scenes. It's important to remember that:
* Pokémon is a show for children: It focuses on themes of friendship, teamwork, and adventure. There would be no reason to include such a scene.
* There's no evidence of this scene: No official source, including episode guides or summaries, mentions foot-tickling Dawn.
* Fan-made content exists: The internet is full of fan-made videos, memes, and jokes that often play with the characters in humorous ways.
It's always best to stick to official content when referencing Pokémon episodes and events.