Covered Up: Bobby Darin's rendition of "Mack the Knife".
Draco in Leather Pants: Macheath is the one character most audiences seem to like best, even though he is intended as a despicable villain. Though of course most productions water down the violence and nastiness of the original a lot, if portrayed the way Brecht wrote him - an amoral pimp, human trafficker and child murderer - this trope is less in play.
Older Than They Think: Several of Macheath's songs are taken from the French renaissance poet (and professional criminal) Francois Villon. It works in the other direction, too: A lot of people are more likely to connect the "Moritat" with Bobby Darrin or Louis Armstrong than Bertolt Brecht.