Tarzaning is using the swing from pikmin chain to sling Olimar up through stages with transparent floors, such as Brinstar, the moving part of Delfino, or hte Moving part of Halberd. You pikmin chain at the farthest distance you can from the ledge, and as soon as you reach around the bottom and start to go up towards the stage, you tap down to break the chain and immediately jump and you can pop up through the middle of the stage. If you do it really well, you can actually tarzan to the other side below the stage and use another chain to tether to the other ledge, lol. But its best use is in popping up through the center. The reason you can't do it with tap jump on is because you'll, most of the time, use your second jump up when you first tether to the ledge, and if you don't have your second jump and you try to tarzan, you just die.