In the fifth episode of the campaign, "Payroll Bandit", use the following combinations:
Fight + Tough Guys = Broken Rib, Dominic, Tough Guys
Explore + Dominic = Bar, Dominic, Minivan
Dominic + Bar = Bar, Seller Pete
Dominic + Tough Guys = Dominic, Gun, Running Louie
Gun + Running Louie = Golden Watch, Money, Wounded Louie
Gun + Wounded Louie + Louie Corpse
Golden Watch + Seller Pete = RPG, Sniper Rifle
Explore + Bar = Bank Clerk
Bank Clerk + RPG = Panic, Route, RPG
The achievement should then unlock.