I've met a few other people with synaesthesia and we all experience it differently. I find it really odd - almost nauseating - to hear that other people think Wednesdays are green, for example, when they're most definitively a dusky rose pink!
Other things that have freaked me out - when my best friend got married and changed her name, she went from being a blue (first name) and green (surname) person, to yellow (surname) which just felt so wrong! I was very pleased when she later got divorced and went back to her original name :)
On the drugs front, in my younger years when I took ecstasy or mushrooms (it was the 90s) I would experience music in 3D. Dunno how to explain it but dance music for example would be like a hard box with defined straight edges that I could feel and I would be 'inside' it, and would fully experience the music as a tangible, pulsating object. More abstract or ambient music I'd experience as liquid, like treacle - I could put my hand out in front of me and 'feel' it.
I'm a musician anyway, so don't know if that has anything to do with it, but suspect quite a lot of people had similar experiences, musical or not.
And that reminds me of my other 'superpower' - I can remember pretty much any piece of music after one listen and sing or play it back on the piano. I can also very easily isolate individual parts in a piece of music. Eg, if you played me a song and asked me to hum back just the bass guitar part I could do that. I can also predict the way the melody is going to go, or sense the entirety of a piece of music before I've heard it all. Some people call this 'audiation'. It's a bit like when an artist visualises the final image before they've painted it. For my masters dissertation I had to write a piece for full orchestra, and I guess that's how I was able to hear all the different parts and instruments in my head before committing them to manuscript.