Playground retort

I CAN SO!

Think of what a child might shout back when someone says they can't do something, often with hands on hips for emphasis.

This clue references a classic childhood comeback you’d hear on the playground when someone doubts you. "I CAN SO!" is the defiant reply to a challenge like "You can’t climb that!"—it’s playful, exaggerated, and full of kid energy. The phrase mimics the back-and-forth teasing that’s common in schoolyard banter, making it a nostalgic fit for a crossword.