Heh, it's a long story.
It goes back about twelve to eleven years when I first started playing a java-based MMORPG RuneScape that I played for over eight years after that and that first got me to online communities, and, in fact, eventually even got me here. It was a sort of an open world fantasy RPG where you could do everything from killing monsters to becoming a master woodcutter by chopping down thousands of trees (at one point I spent four straight months just sitting near some yew trees and chopping them down for three hours in a row - the full duration of my allowed PC time at that age), so I figured, at the age of nine, I wanted my character to have a fantasy name that wouldn't be too childish and lame but that would still incorporate the fantasy charm.
I had seen my friends play the game and had seen them come across players with names like Sir or Lord or Knight something something, and at the time it struck me as a good idea to emphasize the fantasy aspect of it by choosing something similar, so I decided that becoming a Lord sounded the best. Then I started thinking about things I really liked because obviously it would have to be a personal name, and Netherlands was pretty much the first thing that came to mind. I had been there for a few days with my Dad a year earlier and had absolutely fallen in love with the place (my life's most amazing birdwatching experience took place there, and it's something I will always remember with warmth), and having been a fan of their national soccer club earlier I knew Dutch names often had prepositions like Van or Van der that I loved the sound of. So it had to be Lord van Something.
But then I was in trouble. The maximum character limit was 12, and since I already had 9 characters as spaces counted I had to come up with something very short that would sound nice. And I spent hours thinking about three-letter words that would make the name to no avail. Everything just sounded awful. Then I got frustrated, stopped, and went to the bathroom, only to see my young sister's pack of diapers lying on the floor. And it had a huge text Pampers Baby DRY on it, with the last word completely in caps. I instantly knew I had it down. Lord van Dry sounded perfect.
And I stuck to that for as long as I played the game. They even implemented a name change option years down the line which lead to the vast majority of people who were unhappy with their original name changing their in-game names. I never did. The only problem arose when I started using IRC and realized an in-game name like LordvanDry looked absolutely hideous in an online chat where the context was completely different. It had to be changed, so I just took the only part of the name that I could make use of and inflected it. I didn't even have to think, it all came to me in an instant. I translated 'dry' in Finnish and added the -ish suffix to it in an ironic joke on my habit of being very matter-of-fact and dry whenever talking about something seriously. Then I later translated it back into English again when I started frequenting international boards.
And it's honestly the perfect name for me. Anyone who knows me really well knows that I'm not really a dry person at all, and that I don't really want to be one, but that I have a natural tendency of sliding into that kind of a role everywhere after having spoken in that way for a couple of times. It comes effortlessly, and it's a very fun image to spread around because it often lets me catch people by surprise when I do something that they never expect of someone as dry and boring as me. So by sticking with the name, I both embrace that role and simultaneously laugh at myself for being that way when I really am not. It's funny, simple, accurate, delightfully intelligent, ironic, and sounds really cool. And I absolutely love it like I always have.
The reason I love my parrot avatar so much ties into it too. It's funny to have a colourful avatar that in a weird way represents a colourful view of life and goes to show that I appreciate the beauty of it all when I my name is something that deliberately goes against that. Also, I just love parrots.
Tl;dr: "Dryish" comes from a pack of diapers.