The Shakiest Gun in the West (1968)

Jesse W. Haywood graduates from dental school in Philadelphia in 1870 and goes west "to fight oral ignorance." Meanwhile stagecoach robber Penelope "Bad Penny" Cushing is offered a pardon if she will track down a ring of gun smugglers. She tricks the bungling Haywood into a fictitious marriage as a disguise, and he becomes the heroic "Doc the Haywood" after he guns down "Arnold the Kid" and performs other exploits with Penny's help (unbeknown to him or anyone else).