This short oh clip circulates on user generated soundboards under the shortened name legoh, with the longer drawn out spelling legoooooh used in its original listing. No clear original recording, character or release is documented for it, so its history is mainly an online one. Short reaction sounds like this spread because they are easy to preview, download as MP3 and reuse instantly. It has stayed in use as a lightweight punchline for Lego themed posts, toy videos and general meme edits where a quick vocal reaction is needed.