Difficulty: Moderately Easy
Step1
First, pull the elbow off the top of the straight piece of pipe and lay it on the ground.
Step2
Now pull the straight piece up and lay it to the side as well.
Step3
Pick the elbow back up and drop it to the hole in the wall on the left.
Step4
Now you should be able to switch to Bart, float up to the middle platform and then jump and float over to the left platform where the Krusty Coupon is.