Turns out the clown is actually me.
A self-mocking meme.
Clown refers to those who willingly lower themselves in order to please someone else (usually female). Some of these people could be continuously in denial, deeply entangled in their own fantasy. This meme marks the very moment that a clown-in-denial finally realizes the ugly truth, and bitterly remarks the futility and ridiculousness of his previous sacrifice.
However, the growing popularity of this meme has brought a new and less bitter interpretation. When a person starts doing something that he openly rejected in the past, this meme can be used to poke fun of his self-contradictory behavior. In some way, the new interpretation is similar to the renowned Yummy meme.
The "clown" can be further replaced with other words based on the context.
e.g.
Streamer: Dr. Pepper? Only nerds drink that. Not my cup of tea.
Listeners saw empty Dr. Pepper cans in streamer's garbage can.
Comment: Turns out nerd is actually me.