This is kinda dogshit advice and doesn't really help with writing his speech patterns necessarily but a problem SO MANY people have when writing dave is thinking too hard about writing him accurately. Doesn't mean you shouldn't think about it, but generally if something flows naturally it's probably pretty in-line with some stupid shit he'd say. If you go too hard on the teh epicz sicknasty ironic oneliners you end up with a cardboard cutout of dave.