Stupidly sentimental. Maudlin drunk is the drunkenness which is sentimental and inclined to tears. Maudlin slip-slop is sentimental chitchat. The word is derived from Mary Magdalen, who is drawn by ancient painters with a lackadaisical face, and eyes swollen with weeping.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894