I've got several, with examples:
- Completely discounting a game or platform having any value because it is not the best in it's field.
Ex. - Trying to get my casual friends to play Timeplitters 2 or any other non-Halo2 FPS for a change. "This game's not as good as Halo2! Let's play Halo2 some more!" or upon seeing me play my DS, "The pictures of the PSP look so cool, why would anyone buy a DS? I don't understand it." Basically, in their view there is no gradient of quality or variety of gaming. It's either the best or it's utter crap.
- Completely discounting a controller or control device upon using it for 5 minutes.
Ex. - "I can't use the mouse and keyboard for at the same time! Computers suck for games!" or, upon switching from GC to Xbox for Tiger Woods golf "This controller is harder to use and more complicated. You should've got the GC version again this year! I don't even want to play!" Me:"It's no harder to use you nimrod, you just have to get used to it again! Give it time!"
- Completely ignoring my advice after they ask for it, knowing I am a hard-core gamer.
Ex. - Casual gamer friend asks what game system to buy. I explain that while all have good games, thier casual tastes would be best served with an Xbox or PS2. They notice I am playing GC. "These Nintendo games are fun" they say, and I reply "Yes, but they cater to a certain crowd. You'd be better off with a mainstream system". A week later they purchase a GC anyway. A month later they are lamenting the fact that 3rd Party Game X isn't on the GC and they should've gotten PS2/Xbox. "I tried to tell you, dammit!"
- Mishearing a japanese phrase in a game and then running it into the ground.
Ex. - When I got SF2 for SNES, my mom and dad swore Ryu and Ken were saying "A-Bullshit!" instead of "Hadoken!". Now, years later, every time my Dad sees me playing any SF related game whatsoever, he starts his Ryu-like "Abullshit!" up. So annoying.