Only one weird quirk..?
1 - During breaks, mash ZXZX as fast as I'm capable of (regardless of whatever the map's speed is), while jumping between far points in the map's background image that can be "targeted" (like character's eyes, fingertips, etc), and if there are no points like this then just jump between the four corners on the screen in no particular order.
2 - When spinning, I raise my left leg until it touches the tablet's bottom, lean forward, and stay like that until I'm done spinning. Also while spinning, I scream "FIREEEE" inside my head, not in real life tho :p
3 - When playing multiplayer, after every spinner, quickly hit F8 and write how much I spun then F8 again and keep playing. I only type the shortest message possible i.e. for example "8k" without the "".
4 - If there's a slow part in a map relative to other parts of it, I jump to nonexistent places between beats. i.e. if there's suddenly a 1/1-1/1-1/1-1/1 section after a lot of 1/2s and 1/4s, I will a 1/1 -> 1/1 like a 1/2 -> 1/2 -> 1/2 with two jumps in the middle.
5 - If a repeating slider suddenly shows up and I'm not sure how to time it correctly (on very high bpm maps) I will just ZXZ the beginning of it before holding it down.
6 - I love playing maps that I couldn't clear normally with HalfTime. Dunno if this counts as a weird habit~. For example Lily - Scarlet Rose is really fun for me with HalfTime even though I have no chance to clear it normally right now :L
7 - If I'm still on 100% accuracy past the first 20% of a map, I will constantly be looking at the accuracy display, even though I know that eventually it will make me get a 100 in an unexpected spot.
Also I have the same problem as Salvage and ychao24... my best run on a map is the first run, if I try to re-play I get it worse...! wtf. So I just play many different maps, and bookmark maps that I liked to re-play some time later.