Just do it.” With three short words, more famous for selling sports gear than exposing conspiracies, star witness Michael Cohen on Monday depicted Donald Trump’s order of a hush money payoff to an adult film star to allegedly save his 2016 campaign. Prosecutors will seek to build on his testimony when he returns to the stand Tuesday to nail down their case that the ex-president broke the law by falsifying financial records to hide the pay-off in the culmination of a scheme to mislead voters.