also: つうといえばかあ
quick to take a hint; very responsive; quick on the uptake
Describes a relationship or person where a brief cue (like 'tsu') immediately gets the right response ('ka'). Often used for close friends or smooth teamwork.
See also: ツーカー
Those two are so in sync that a single word gets an instant understanding.
He's so quick on the uptake that he barely needs any explanation.
Standard katakana spelling for this colloquial phrase.
Hiragana variant; less common but still used.
From the idea that saying 'tsu' immediately prompts 'ka' in response, mimicking a quick, intuitive exchange. The exact origin is uncertain, but it's a colloquial metaphor for smooth communication.