OOOOOOH if we`re talking about morse code used in homestuck soundtracks Indigo Heir uses the code for SOS near the end!
Heh, now that’s one that I did pick out pretty immediately, if only because the SOS Morse code pattern (… —- …) is probably the most famous and used bit of code there is. It’s used in movies when ships are sinking, and it’s used to sell cookware cleaning accessories. It’s everywhere!