There is a glitch were you can shoot through the wall with the rainmaker at Inkblot Art Academy just behind the enemy spawn point. I found this one while playing around when I was bored. After finding it... Me: WHATTTTTTTTTTT! *Does it over and over*
Amazingly, Nintendo NEVER patched this, and it will likely be in Splatoon 2 forever now lol. Plus, you can access this room even when your offline, so it'll always be possible, even years later when the online service inevitably closes.