There are many memes that people recognize and know because they have heard them so often. In the case of Captain America, his meme is Hail Hydra or Captain Hydra because that is what is associated with him. Hydra is an organization known for its military for terrorism. It should not be strange to know that Captain America is an agent for Hydra and he is known through his alter ego who is Steve Rogers.
Even though Captain America has been around for decades, this saying “Hail Hydra” only came recently. During the last panel or picture of a comic issue in 2016, Captain America says “Hail Hydra.” This resulted in people associating Hail Hydra with Captain America and Steve Rogers.