What's the most unusual hair cut or colour you've had?

Used to have spikes like Scott from Five with different coloured tips like red and green.

once orange, once purple on accident, and big bird yellow once on purpose-ish

on accident
by accident :)

I've had pink and purple. I loved the pink!

Shaved a mohawk into my hair once on the first day of school holidays. My mother reacted to it as if I had just confessed to doing heroin, so my mohawk soon became just a shaved head.
Had blue hair for a couple of weeks during another school holiday. I've got a thing for blue hair actually.
Long dreadlocks, like down to my ass. In my early 20s. I loved them but I'll never do that again because they're a huge amount of effort to maintain and keep looking good.

Since then I'm either just letting it grow or cutting it down to about 2mm. No in between. Currently haven't cut my hair for around a year and a half and I don't plan to any time soon (although I have been kinda dying to try an undercut).

I'm surprised dreadlocks are a lot of effort... I thought they kinda managed themselves?
- I found that to be a misconception, personally. I guess it could differ with hair types but in my case at least, the longer it gets left, the more it just looks like a nest of knots. Also you can end up with your hair matting together and dreadlocks just straight up fusing if you don't look after them. Plus you get bed dreds, dreadlocks at the back of your head that get squished flat after a while if you leave them. And also just want to throw out there that clean hair is the best condition for them and the dirty hair thing is a load of BS too.
  Like, I guess you could get away with ok looking dreadlocks with relatively low maintenance but if you want awesome, healthy, clean looking dreds, you have to firstly keep them clean but also spend a lot of time on your hair rolling them and neatening things up basically daily.

shaved a spiked into a tri-hawk, gradient from dark purple at the roots to hot pink at the tips

No hair, longer than shoulder long hair and blue hair.

Ich can't decide which I found more unusual.

However since then I know that I can never go bald, my head is shaped like an aliens head and it looks weird.