Bow Wow Skip is a critical Skip that allows you to get into Bottle Grotto without having to rescue Bow Wow. The trick involves doing a Like Like Launch to get on top of trees, then walking on the swamp bramble and jumping over the flowers from there.
Here's a tutorial that covers how to execute the trick:
Notes: Doing this trick results in you being "soft locked" in Bottle Grotto until you obtain the Power Bracelet from that dungeon. Obtaining the Conch Horn before rescuing Bow Wow and then attempting to rescue Bow Wow results in a softlock upon exiting the Moblin Cave. It can be avoided by playing Manbo's Mambo to exit the cave or by obtaining the Full Moon Cello after obtaining the Conch Horn.