Owe 90k worth of jewlery U.O.E.N.O.

Rick Ross has just been sued for being so sophisticated ... he forgot to pay a nearly $90,000 bill for three Rolexes he bought last year -- this according to a new lawsuit.

Johnny's Custom Jewelry in Texas filed the suit against Ross and his company Maybach Music, claiming the rapper agreed to purchase 3 diamond Rolexes last August for a total of $89,847.50.

According to Johnny's, the Rolexes include one 18K gold watch with 30CT of diamonds ($55,000), one 18K gold watch with 7CT of diamonds ($14,000), and one two-tone watch with 5CT of diamonds ($14,000).

Johnny's says it held up its end of the bargain -- delivering the watches as ordered -- but Rick still hasn't paid for the bling. Johnny's wants the rapper to cough up the owed money stat, plus interest.

Calls to Rick's people weren't returned.