Player get random Skin AND Cape WITHOUT Plugin?!

Hi,

My friends and I playing Minecraft on a Hamachi Server. Yesterday one of them changes his Skin from the Default-Guy to a weird looking blue Thing. (He doesn't own the game and told me he doesn't do anything)

My first idea was, that someone who bought the game and uses the name David changes his skin, so the server loads this skin like he loads my from minecraft.net.

But today he's wearing a red cape!

Our server has no plugin that could make this possible and he doesn't have the skills to manage this alone also he has no access to the server files.

We're using the recommended build #1240

Server Plugin List:

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AdminCmd
Bedheal
BlocksOnGlass
ControllerBlock
CreativeGAtes
FunCommands
HeroicDeath
mchange
MinecartMania
NoMelt
PaintingSwitch
PickBoat
Ptweaks
QuantumConnectors
Safe Creeper
Scavenger
SelfClosingDoor
UnderWaterTorch

Single Player Mods (Running on 1.8.1)

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ModLoader
Water Shader v4_D
OptiFine 1.8.1 S-A
WaterShader + OptiFine Compatibility Patch
SoundModEnabler
BetterSounds
BetterGlass
ReiMinimap 2.0
TooManyItems 9.14

He:

 

That's a Minecon cloak. http://mojang.com/2011/09/27/minecon-speakers-the-yogscast/