Uhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh ignore everything I said. Robo Spongebob has another spatula hidden under the stage, and it doesn't end the fight AND after collecting it, it doesn't show up on your pause screen O_O
Edit: here's a video
http://www.youtube.com/watch?v=0JHBoiK01io
Also this is just that weird glitch, like the one in rock bottom, where the spatula is gray even though you have it. At first I thought this meant there were [at least] 3 extra spatulas hidden in this game, but sadly that's not the case.
Since this didn't end the fight, it would seem that more happens than I thought earlier. Here's what we do know: After doing the final hit, you're warped to that trigger above the first platform, then during the cutscene you collect the spatula under the stage. There could be more steps to that for all we know.
Also this raises the question of, is it the spatula or the invisible trigger that gives you upgrades? If it's the spatula, then assuming we find a way to reach the spatula in the robo sandy fight we could just collect it and leave since we'd have the spatula and upgrade. If it's the trigger then even if we find a way to the spatula, it would be useless. In either scenario, if there are invisible triggers in Sandy/Patrick's fights, we can skip the fight and get the upgrade.
This needs more testing.
Edit: Someone please go find a code to either die or get grabbed by the hand. I've been trying forever and I'm terrible at this kind of thing.
