The Side Eye Horse meme features a horse glancing backward with an incredibly human-like expression of suspicion, judgment, or skepticism. While various images of horses giving 'side eye' have circulated for years, the template gained significant traction on platforms like TikTok and Twitter as a visual shorthand for the 'bombastic side eye' trend. It is perfectly suited for situations where words aren't enough to express your disbelief or when you catch someone in a blatant lie. Its popularity stems from the absurdity of a large animal conveying such complex, sassy human emotions, making it a staple in the reaction meme hall of fame.