Rembrandt Photo
::click:: Come back! You didn't see the one of Whistler's mother!
::click:: Come back! You didn't see the one of Whistler's mother!
Rembrandt was a 17th-century Dutch artist. Megan shows Cueball an alleged photo of Rembrandt's parents at the time that his mother became pregnant; his conception. Since photography wasn't invented until the 19th century, it can't be a real photo. Megan responds to Cueball's disbelief by stating that it is an artist's conception: an artistic imagination and depiction of an event.
The joke thus is a pun on the phrase 'artist's conception' that can mean two different things: one, Rembrandt's mother becoming pregnant with him and two, the creation of the image.
The title text refers to James McNeill Whistler who painted a portrait of his mother, known to Whistler himself as "Arrangement in Grey and Black No1" but more commonly known as "Whistler's Mother". As a joke on this, Megan seems to want to show a photo of Whistler's mother, which would probably be pornographic or at least different from the famous portrait. The ::click:: is Megan switching to that picture on her laptop.