have calluses from patting own back
have calluses from patting (one's) own back
To have excessively praised oneself for an achievement or a job well done. Tony was instrumental in the success of the merger—or so he says. I bet he has calluses from patting his own back.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
have calluses from patting one's own backand 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.
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs. © 2002 by The McGraw-Hill Companies, Inc.