When you unlock Vanilla secret 2 beat it and hit the half way point, BUT dont finish the level instead pause go back re-enter and collect the grey P-swich and go to the pipes with the jumping plants. hit the P-swich and then go and the grey coins to the LEFT <-. then you hear "whoo hoo! Bravo Mario" (i think) its says after 2 flowers come on the screen between them it says ??up! the "??" mean how many 1ups you should get around 25 grey coins and 51ups if done correctly.

(Note:There is a video of this on www.youtube.com)