Zombie head
Charlie's sleeping bag was removed from RuneScape after Update:Ninja Fixes to Invention - Live Stream Info - Other News, but still exists in-game for those who had obtained it.
[FAQ] • [doc]

Charlie's sleeping bag is an item used in Meg's cases. It is dropped by Zombies in the Varrock Sewers during the Charlie's Missing Sleeping Bag case, and must be returned to Charlie to complete the case. It can be investigated in order to obtain a Grand Exchange receipt.