Duìbùqǐ means “I’m sorry”.
In a crowd you bump into somebody and snap “Du!” at them – the German word for “you”, said sharply, carries the falling tone and gives you duì. By way of apology he hands you a book with sharp edges: book (Buch in German) and the sharp edge give you bù, also falling. Inside the book it describes how people in India dance the cha-cha-cha, on a trampoline: cha and India give you qǐ, with the trampoline marking the third tone.
You can see how the pitch moves into the image – and how that makes you confident without learning the tones separately.