In Poseidome, there is a boss fight against Robo-Sandy unlocked after collecting 15 spatulas that also opens the player up to Hub 2. Poseidome clip is a lag clip used to grab the spatula in the Poseidome without having to fight Robo-Sandy. This trick is not possible on Gamecube or Wii.
Poseidome clip requires the cruise bubble and bubble bowl to achieve. Once loaded into the level, perform a slow cruise boost along the wall without inputting any direction on the control stick. Wait for sandy to slam and launch spongebob up high. At the apex of the height, perform another jump. Line up against the wall to start a cruise bubble and pause mash to clip through the ground. On systems that lag more such as 360 and PS2, you can also reliably do this trick in the middle of the stage by mashing L inbetween pauses like in Drain the Lake Clip. The spatula will be waiting for you below the stage.
The spatula does not trigger the ending cutscene of the boss fight, meaning that even if done without the bubble bowl, this clip will not unlock the bubble bowl. However collecting the spatula updates the game's pause screen to show that Poseidome has been completed. It also causes you to talk to plankton upon next visiting bikini bottom and removes the barrier between hub 1 and hub 2.