TV's Frink said:
I've been looking at that last one for about five minutes and I still can't figure it out.
Panel 2 Goofy notices that Panel 4 Goofy - who exists in the future - is wearing an extra hat, so he reaches down and steals Panel 4 Goofy's extra hat. Panel 2 Goofy then transitions into Panel 3 Goofy, who is wearing two hats, and, eventually, into Panel 4 Goofy, who is the same Goofy he stole the hat from in the past when he was Panel 2 Goofy. At this point, Panel 4 Goofy's past self - Panel 2 Goofy - reaches into the present of Panel 4 and steals his extra hat. From here on out, the Goofies of Panels 5 & 6 only have a single hat, with the extra hat locked in an eternal time loop.