• When I do something well, and no one compliments me, I literally pat myself on the shoulder and say "Good job, Larissa!"
• There is a spider who lives under a small shelf in my shower, about six inches below eye level. I refuse to kill him and I've named him Max. I also talk to him while taking showers.
• I get into heated arguments with the radio. And songs. And movies. And videos. And literally any sort of media that expresses an opinion that I disagree with. (All in fun, of course.)
• Whenever I need to make a decision I'm indecisive on, I write out pro/con charts and assign different weights for each pro and con, based on how important each one is. Then I calculate the score for each side, and whichever one wins determines my decision. (Higher pro = yes. Higher con = no.) It works quite well, but people seem to think it's weird.
• If I start to tap my foot or my fingers, I have to finish in a certain pattern, or else it bothers me greatly.
• I count every tile I step on, and I refuse to step on any cracks. Just imagine my pain when I have to walk across a place made of teeny tiny bricks.
• I have to listen to music while doing homework, or else I will get distracted.
• In order to cope with my parents' fighting, I listen to them and mentally come up with better responses to their arguements because usually they're pretty nonsensical.
• Whenever I feel like I'm about to cry, I insult myself about it. It works like a charm and I stop myself right then and there.
• I'm order to stay composed, I critique people's faces while they're yelling at me.
• The zippers on my backpack have to be at the top when I zip it up.
• One of my knives has to be under my pillow before I go to sleep.
• I sing about mundane tasks while doing them. It makes it more interesting.

That's all the weird things I can think of for now. I'm sure I'll remember more, and when I do, I'll add them.