DAM is Day After Monday, and the syndrome is typical of crabby, caged behaviour of office goers. It's worse than Monday as the relaxation of Sunday has been long forgotten &Friday is a long way away!
eg 1:
She: My boyfriend is behaving funny today
He: He'll be better tomorrow. He must be suffering from DAM syndrome
eg 2:
Ms. Depressed: I feel terrible even after coffee
Ms. Chirpy: It's Tuesday. You prolly have DAM Syndrome. Nothing serious :)