By TMZ

UFC superstar Conor McGregor has landed in Beverly Hills, California -- and he's spending crazy money and talking smack!

We got Conor in the middle of a super expensive shopping spree at Versace, Dolce, etc -- where he told TMZ Sports, "I'm on Rodeo Drive! I'm blowing f***ing loads of it!"

McGregor is in town for the start of his four city media tour to promote the upcoming showdown with Floyd Mayweather Jr. - which takes place on August 26th at the T-Mobile Arena in Las Vegas. The fight will be available on Showtime Pay-Per-View for $99.95 in HD.

The media tour will start tomorrow in Los Angeles, and will also touch down in Brooklyn, Toronto and London. The 40 year-old Mayweather, who retired back in 2015, will hit the ring first time since dominating Andre Berto over twelve rounds in September of that year.

For McGregor, it will be his professional boxing match, and it takes place at the junior middleweight limit of 154-pounds with 10-ounce gloves being worn by both fighters.

We also asked McGregor about reports that Mayweather owes a lot of money to the IRS for not paying off his 2015 income taxes ... a number that some estimate could be in the tens of millions. Mayweather has filed for an extension with IRS to settle his bill in full - telling the IRS he'll pay them after the McGregor contest takes place. The IRS however would like to get the money now and they advised the undefeated fighter to sell off some of his assets.

"That's gotta sting," McGregor said ... "He shoulda paid his taxes and stayed retired and kept my name out of his mouth!"

He also told us he'll be way smarter with his money ... as he continued to drop thousands at some of the most expensive stores in the world.

Conor also had one last note about Floyd -- "He's f***ed now."