A Daddy in gay culture is a slang term meaning a man sexually involved in a relationship with a younger male.[1][2][3]
In an internet meme context, Know Your Meme defines the term as a "slang term of affection used to address a male authority figure or idol in a sexualized manner."[4]
In BDSM, a "daddy/boy" relationship can share similarities with a dynamic of dominance and submission.[5]