Heh, my 6-year-old kid just managed to do this: Mario talked to the guy in the Blooper Surfing Safari shine course (when he explains what you have to do), and when he said "choose a blooper and hop on" or whatever he says at the end, Mario went over to the bloopers---and there were only two there :-) The green and yellow---no pink one. I'm sure this is an old trick, but I'd never seen it done before. You all know how he did it, right? Thought so.
The shine in the plaza behind the door that you have to break, guarded by two piantas---he broke the door earlier today but didn't go in, and then went in with the hover nozzle. He almost got the shine---just missed the last jump. But I bet it's possible, right? Can you do it with the rocket nozzle? Again it looks like it should be possible.
He did it like this: when he fell into the level he held the joystick to one side and didn't trigger the speech from the guy down there. He then went around with one blooper and when he got around, he triggered the speech but had used up a blooper.