Elaine had to take a sick day at J. Peterman because she was sick of all the cake parties and the forced socializing that went along with someones last day, birthday, sick day etc.etc..
When she got back to work the next day they had a cake for her and all her co-workers sang "Get well, get well soon, we wish you to get well." They also had a get well cake for Walt who as J. Peterman said "Poor Walt has a polyp in the duodenum. It's benign but oohh still a bastard." When Peterman heard the get well song he thought it was "A stirring little anthem of wellness."