To expand on your edited bit, use those words exactly. Don’t use slang or anything else. Explicitly invoke your right to remain silent and leave it at that. The supreme court rules that police “misinterpreting” when a guy asked “for my lawyer, dawg” as “for my lawyer dog” (which you don’t have a right to) as reasonable. They will attempt to ignore your rights if they can. Also, IIRC, speaking after invoking your right to remain silent means you are no longer invoking your right to remain silent, so if you speak then you should invoke it again.