Okay, load coder. go near pipe or ladder and open the coder window. tap W so that your character stops the "coding" animation but still has the coder window open. now you should be able to click on other stuff. double click a pipe while simultaneously holding S. this will cause your char to do the climbing animation then "zap" back to the ground. If you have the climbing back down animation normally, it didn't work. You will know it worked if you can't jump. You look like you're standing but you're really doing the pipe animation while moving around. If you go to an area lower than the y value of the pipe you will also look like you're floating to other players.
Now you can walk around like this. If you try to walk into a wall, you will pass through the wall by a few feet in the eyes of other players. Try typing in a /mood and the bug will change. Now you can move up and down but not around. you can use this to climb anywhere, but if you go lower than the y value of the pipe's base you get zapped back to the pipe's base. If you go higher than the y value of the top you also get zapped back to the top. If you do this from very far away from the original pipe you will also get a weird-looking bug that "knocks" you around for a couple minutes.
Also, one more bug you can try is doing the pipe glitch then going to a door. You will need another person for this. Just keep clicking on the door and it will give a message saying you can't open it(because you aren't standing). but while you're clicking have a second person actually open the door and the bug will change again. Now you will also be able to walk through walls. If you do the door bug at a location with a y value lower than the ground you started on, you will also be zapped into the air and can still walk around as such. Keep in mind that this bug no longer works if you try to go up a slope.
Sometimes you will get a bug where the W key won't stop you from coding when you use the coder window. If this happens, simply /suicide, and it should work correctly again.
I hope they don't fix this stuff, it's kind of fun to do, I'm addicted
Edit: Clarity, and added a bit more. How many Yay do I need?