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general::
Phrase(s): have calluses from patting one’s own back [and] break one’s arm patting oneself on the back
Fig. to be a braggart. • If you haven’t heard about Bill’s latest achievement, he’d be glad to tell you. He has calluses from patting his own back. • Jane: I did a really wonderful job, if I do say so myself. Tom: If you’re not careful, you’ll break your arm patting yourself on the back.
McGrawhill's American Idioms And Phrasal Verbs