World 4 - Level 9
To solve this level you need to get the two boxes from the top left corner and place them onto the two buttons close to your starting position.
Move Stinky left (carefully time your steps with the guarding Flying Saucers). Enter the ice along the green path first. This will destroy the Saucers marked in green. Exit and re-enter along the blue path. This will destroy all but one Saucer marked in blue. You can now move up the central path and retrieve your boxes... just be careful to once again time your steps with Flying Saucers.
(A Hint: wait until they're coming toward you and are exactly one tile away from you. As they begin to enter "your" tile position, start moving toward them. You and them will pass each other without a shot being fired).