have nothing on
Also, not have anything on.
Have no advantage over something or someone, as in This car has nothing on my old one. [c. 1900]
Have no damaging information or proof of wrongdoing about someone, as in The police had nothing on him and so were forced to let him go. This usage is the antonym of have something on someone, as in Blackmail requires that you have something on someone wealthy. [c. 1920]
Have nothing scheduled for a certain time, as in We have nothing on tonight, so why don't you come over? This expression, and its antonym, have something on, are abbreviations of have nothing (or something) going on.
Be naked, as in Please bring in the mail; I just took a bath and don't have anything on.