Floyd Mayweather -- STACKS ON STACKS ... Drops $50k at MIA Strip Club

It was good to be a stripper in Miami on Monday night ... when Floyd Mayweather rolled into King of Diamonds and lit the place up with a $50,000 thunderstorm ... TMZ Sports has learned.

Sources connected to Floyd tell us ... after he got his brand new $3.5 million Bugatti supercar, Floyd was still itchin' to spend more dough -- so he organized a TMT outing to K.O.D ... 45 PEOPLE DEEP!!

Besides busting out the stacks of cash, we're told Floyd ordered 30 bottles of champagne!!

BTW, one source who was there tells us there was so much cash being thrown around, you couldn't see the floor ... and staffers busted out brooms to sweep up all the bills.