IRS was filing lawsuit against me. When I couldn't understand the first person and asked to speak to someone else to answer my questions, he said "oh f*** you" and hung up. I called back and spoke to a woman and although she had all the same info as the the original caller she told me "this is not for you, wrong number".
Automated voice claiming to be the IRS. Sounded fake as they never identified who was they're trying to reach, other than saying "you". Checked here, and it's definitely fake.