The sussy part comes from Among Us slang that spread widely online in 2021, when sus and sussy became shorthand for anyone acting suspicious. This longer what da heeeeeel version builds on the familiar shocked exclamation by dragging out the vowel for comic effect, a style common in soundboard and meme edits. It circulated as a shareable reaction clip rather than a scene from a film or show, and it stays popular because it fits gaming lobbies, impostor accusations and any moment that feels both wrong and funny.