Pronunciation: [ðatðɪ a͡ɪdˈi͡ə] (IPA) 
The spelling of "that the idea" is fairly straightforward. "That" is pronounced /ðæt/ (like "thuh-at") and "the" is pronounced /ðiː/ (like "thee"). "Idea" is pronounced /aɪˈdiːə/ (like "eye-dee-uh"). So, when combined, the three words are pronounced /ðæt ðiː aɪˈdiːə/. Remembering to include the "h" in "that" and to use "the" instead of "tha" will ensure correct spelling and pronunciation.
That the idea is an idiomatic expression used to indicate surprise, disbelief, or astonishment towards a particular statement or action. It is often used in informal conversations and is employed to emphasize the speaker's reaction or commentary on something unexpected or extraordinary. The phrase is commonly used to express both positive and negative reactions, depending on the context.
The expression can also convey a sense of agreement or approval towards a suggestion or proposal, showcasing enthusiasm or excitement about the concept being discussed. In this context, "that the idea" can be perceived as a way of saying "that sounds fantastic" or "that's brilliant."
Furthermore, the phrase is likely to be accompanied by a variety of tone and body language, such as raised eyebrows, widened eyes, or an incredulous tone of voice, contributing to its intended effect.
Overall, "that the idea" is a versatile expression often used colloquially to express surprise, approval, or disbelief in response to something unusual or unexpected. Its usage is primarily seen in spoken language, allowing for a more expressive and spontaneous conversation.
