He doesn't go by "Bob" or "Bobby" or "Rob" or "Robbie." He goes by "Robert," because that is his name. "Robert" is what his birth certificate says and what his mother calls him, and when he introduces himself as "Robert," he sees no excuse or reason for people to call him otherwise.
This is why it is especially hard, right now, in this cramped little office, in this shirt with a collar just a little to tight, to listen to the man across the desk who is describing a job offer. He could ignore the bad paint-job and the neon signs on the walls, even the tightness around his throat, if only the man would get his name right.
"So, Bob, I see you have an impressive resume here," the man across the desks says, as he surveys the sheet of paper in front of him.
"It's 'Robert'," Robert says, "and thank you." He can see his name across the desk on his resume, on his application, on his business card. The "R" at the front is large and dignified, so he signs it that way on his checks and on his bills and on the application that the man across the desk is now picking up. He puts a finger between his neck and his collar to loosen it a little.
"So why'd you leave your last job, Bob?" The man across the desk chuckles at his rhyme and, in reading the application, seems to have forgotten that he even asked. Robert has begun to hate the man's round, flabby face and his sweaty bald head, and he brushes back his thick brown hair, reminding himself that he isn't bald yetm that his life still has a long way to go, and that unemployment isn't the end of him.
Despite the reasons why he left the Mifflin Corporation, he's a shoe-in for this job, and he'll finally be able to pay his own rent again so that he won't have to stay with Mother any longer. But his name is "Robert", and his collar feels tighter and the man across the desk looks like everything he wants to avoid. That beautiful "R" on his application has been smudged by teh large sweaty of the man across the desk, and he can hardly bear the thought of his name without its crowning glory. He imagines his name in the hands of another: someone, anyone else. This man across the desk does not deserve the beautiful "R" in front of him, does not even deserve to speak the name "Robert" if he can not appreciate its superior beauty.
Robert sits still a little longer, these thoughts predators on his already weak mind, and he thinks how nice it is at Mother's. Unlike this sweaty, bald man across the desk, she would never think to desecrate his name.