Since pictures are, after all, worth a thousand words, we introduce our two champions of cheese-ball crime fighting, one whom debuted alongside Steel Sterling in Zip Comics #20 in 1941 (lasting until issue #35). He returned in Mighty Crusaders #4 and then waited until 2001 before joining that team in Archie's Weird Mysteries #3 as they battled a legion of villains in a parallel universe.
The Prankster was introduced in Peter Cannon...Thunderbolt's #60 in 1967. Prankster's second scheduled appearance was never to be as he and his Ultrapolis faded away. One was a product of a classic past era, the other of a potential future era. Both fought the establishment that they lived within and did so with a reckless abandon. Note their differing styles, with Blackjack's panels on the left and Prankster's on the right.