A businessman who is always talking about how smart and rich he is and who is constantly telling you why he is the best person to manage your business is an example of someone who is bumptious.
Origin of bumptiousprobably from bump, by analogy with fractious
Origin of bumptiousPerhaps blend of bump presumptuous
(comparative more bumptious, superlative most bumptious)
Probably a play on the pattern of words like fractious.