surely it would be easier to go to the nearest shop and buy a cake instead of risking life and limb to get that one... come on !!! £5 is nothing.
if you filled the room with ***z then would the lava flow over the side and destroy the man milk ?
you could get a group of friends to fetch it for you, bribe them with a slice of said cake then double cross them whilst tossing them into the lava pit.