The second level in Hoo's Woods, there is a third Toad in a "secret" area that you get to only by going into the first tube you see from entering the second level. (A.K.A the tube that leads into the grassy land with the spiky turtle dude.)

Keep walking untill you reach end of that scene. Go down the tube that leads to the little ant dudes in on the islands that are floating in the air. Go to the tube at the end that leads to the place with that flying dude on a cloud. Keep going untill you reach the two tubes. Go into the one that is sticking up because the one in the ground doesn't let you go into it.

You come up into the place were there is a lot of water and a fish and a wheel. go over to the wheel and go onto the dry land. after that, start crying on the wheel until a little caption says, "a loud noise is coming from somewhere!" Go back into the tube you came from and then go ionto the smaller tube. This leads you into the "secret" area.

Go to the left and burn down the bridge. Go right again and get all those coins. After that, go left and fall strait down. Find the toad and finish the level.