A "rambling asshole" is someone who goes on long, incoherent, or self-indulgent tangents while being dismissive, condescending, or rude to others. Their speech often centers on themselves or their opinions, disregarding others’ input or feelings. They tend to dominate conversations with little regard for how their tone or words impact the group.
"They were so obnoxious—just nonsense and buffoonery. I told them they couldn’t vape in my car, and you’d think I had demanded they quit nicotine cold turkey; a real rambling asshole."