"The Internal Revenue Service is the real undefeated heavyweight champion"

He could have been referring to the IRS's credibility for being an awesome opponent when it involves collecting taxes as well as applying tax laws. The expression "unbeaten heavyweight champion" suggests that the IRS constantly comes out on top in battles with taxpayers that try to avert their tax obligations or rip off the system in some way. Additionally, it might likewise be viewed as a humorous comment, recognizing the stress as well as challenges that many individuals deal with when taking care of the IRS.