Wiktionary
bumptiously
adv. In a bumptious manner.
WordNet
bumptiously
adv. in a bumptious manner; "he behaved rather bumptiously and offended the hostess"
Usage examples of "bumptiously".
To drown out criticism, the Coquettes and their male counterparts began to sing a mock-worshipful hymn to the Kokotte, set to a tune so bumptiously catchy that the crowd was soon joining in the choruses.