It's the simplicity of the joke which made it so funny to me.
It reads like a mod instruction, which had me laughing... my French isn't as good as it used to be, but I believe the gist of it is:
Picture 1: "Disassemble your Mac Mini properly, as explained here (link)"
Picture 2: "Throw the unecessary components of your Mac Mini (namely everything inside) into the garbage."
Picture 3: "*drumroll* I present you the 'iToilet'. Who wouldn't be impressed by your new dispenser?!"
Picture 4: "--Something about your mother... I'm too rusty to translate this one properly--"