This is a comic by tinydeerguy with two versions. In the first, Darwin opens the door of the bedroom of Matt Riskely and blushes, thinking Matt is doing something embarrassing. It turns out that Matt only is holding a remote (which was hidden under the bedsheets, and appeared to be something naughty).

In the second version, the punchline is different, as Matt is actually masturbating and is holding his penis.