ITS NOT THAT HARD
For those of you who think this is overwhelming, its really not. 1.5 - 3 hours guaranteed with this method.
1. Go to level 37, "Merry Go Round"
2. Grow 2 times as fast as possible, preferably without dying.
3. Float around avoiding eating anything but sharks. (especially do not eat the piranha power-up)
4. Before you complete the level kill yourself by either running into a bomb, or getting eaten by a clam shell
*NOTE: If you have the Safeguard power-up you cannot die by clam.
5. Repeat as many times as you wish, keep in mind that you have 2 continues that both reset you with 3 lives. (use all lives, continue, all lives, continue, then all lives for the biggest number of sharks in one run through)
*NOTE: You may want to finish the level with a few lives left just in case you actually die, if you get a game over without any continues remaining, the sharks you've eaten will not count.
You must complete the level for these to count towards your running total.
I hope this helped anyone who hasn't gotten this or passed on it because it seemed too overwhelming.